10721821 has 4 divisors (see below), whose sum is σ = 11696544. Its totient is φ = 9747100.

The previous prime is 10721819. The next prime is 10721827. The reversal of 10721821 is 12812701.

10721821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12812701 = 11 ⋅1164791.

It is not a de Polignac number, because 10721821 - 2¹ = 10721819 is a prime.

It is a super-2 number, since 2×10721821² = 229914891112082, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 10721792 and 10721801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10721827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 487345 + ... + 487366.

It is an arithmetic number, because the mean of its divisors is an integer number (2924136).

Almost surely, 2^10721821 is an apocalyptic number.

10721821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

10721821 is a deficient number, since it is larger than the sum of its proper divisors (974723).

10721821 is an equidigital number, since it uses as much as digits as its factorization.

10721821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 974722.

The product of its (nonzero) digits is 224, while the sum is 22.

The square root of 10721821 is about 3274.4191851380. The cubic root of 10721821 is about 220.5072386872.

The spelling of 10721821 in words is "ten million, seven hundred twenty-one thousand, eight hundred twenty-one".