21157704 has 48 divisors (see below), whose sum is σ = 59283900. Its totient is φ = 6808704.

The previous prime is 21157699. The next prime is 21157739. The reversal of 21157704 is 40775112.

It can be written as a sum of positive squares in 2 ways, for example, as 20520900 + 636804 = 4530^2 + 798^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2979 + ... + 7154.

Almost surely, 2^21157704 is an apocalyptic number.

21157704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21157704 is an abundant number, since it is smaller than the sum of its proper divisors (38126196).

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

21157704 is a wasteful number, since it uses less digits than its factorization.

21157704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10174 (or 10167 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 21157704 is about 4599.7504280124. The cubic root of 21157704 is about 276.5813204275.

The spelling of 21157704 in words is "twenty-one million, one hundred fifty-seven thousand, seven hundred four".