21904056 has 24 divisors (see below), whose sum is σ = 59323680. Its totient is φ = 7301328.

The previous prime is 21904031. The next prime is 21904061. The reversal of 21904056 is 65040912.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21904056² = 959575338502272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 152040 + ... + 152183.

It is an arithmetic number, because the mean of its divisors is an integer number (2471820).

Almost surely, 2^21904056 is an apocalyptic number.

It is an amenable number.

21904056 is an abundant number, since it is smaller than the sum of its proper divisors (37419624).

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

21904056 is a wasteful number, since it uses less digits than its factorization.

21904056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304235 (or 304228 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21904056 is about 4680.1769197328. The cubic root of 21904056 is about 279.7960078816.

Adding to 21904056 its reverse (65040912), we get a palindrome (86944968).

The spelling of 21904056 in words is "twenty-one million, nine hundred four thousand, fifty-six".