21512056 has 8 divisors (see below), whose sum is σ = 40335120. Its totient is φ = 10756024.

The previous prime is 21512053. The next prime is 21512063. The reversal of 21512056 is 65021512.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512053) 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 as a sum of consecutive naturals, namely, 1344496 + ... + 1344511.

It is an arithmetic number, because the mean of its divisors is an integer number (5041890).

Almost surely, 2^21512056 is an apocalyptic number.

It is an amenable number.

21512056 is a deficient number, since it is larger than the sum of its proper divisors (18823064).

21512056 is a wasteful number, since it uses less digits than its factorization.

21512056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2689013 (or 2689009 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 21512056 is about 4638.1090974663. The cubic root of 21512056 is about 278.1168530375.

Adding to 21512056 its reverse (65021512), we get a palindrome (86533568).

The spelling of 21512056 in words is "twenty-one million, five hundred twelve thousand, fifty-six".