21760020 has 36 divisors (see below), whose sum is σ = 66005940. Its totient is φ = 5802624.

The previous prime is 21760019. The next prime is 21760031. The reversal of 21760020 is 2006712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 11532816 + 10227204 = 3396^2 + 3198^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21759975 and 21760002.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60265 + ... + 60624.

Almost surely, 2^21760020 is an apocalyptic number.

21760020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21760020 is an abundant number, since it is smaller than the sum of its proper divisors (44245920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21760020 is a wasteful number, since it uses less digits than its factorization.

21760020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120904 (or 120899 counting only the distinct ones).

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

The square root of 21760020 is about 4664.7636596081. The cubic root of 21760020 is about 279.1813674098.

Adding to 21760020 its reverse (2006712), we get a palindrome (23766732).

The spelling of 21760020 in words is "twenty-one million, seven hundred sixty thousand, twenty".