21273021 has 24 divisors (see below), whose sum is σ = 38311104. Its totient is φ = 11050560.

The previous prime is 21273019. The next prime is 21273023. The reversal of 21273021 is 12037212.

It is an interprime number because it is at equal distance from previous prime (21273019) and next prime (21273023).

It is not a de Polignac number, because 21273021 - 2¹ = 21273019 is a prime.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21272985 and 21273003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21273023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14656 + ... + 16041.

It is an arithmetic number, because the mean of its divisors is an integer number (1596296).

Almost surely, 2^21273021 is an apocalyptic number.

21273021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21273021 is a deficient number, since it is larger than the sum of its proper divisors (17038083).

21273021 is a wasteful number, since it uses less digits than its factorization.

21273021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30721 (or 30718 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21273021 is about 4612.2685307775. The cubic root of 21273021 is about 277.0828990716.

The spelling of 21273021 in words is "twenty-one million, two hundred seventy-three thousand, twenty-one".