21356672 has 16 divisors (see below), whose sum is σ = 42546750. Its totient is φ = 10678272.

The previous prime is 21356653. The next prime is 21356689. The reversal of 21356672 is 27665312.

It can be written as a sum of positive squares in only one way, i.e., 19571776 + 1784896 = 4424^2 + 1336^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a super-2 number, since 2×21356672² = 912214877831168, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a plaindrome in base 13.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83297 + ... + 83552.

Almost surely, 2^21356672 is an apocalyptic number.

It is an amenable number.

21356672 is a deficient number, since it is larger than the sum of its proper divisors (21190078).

21356672 is an equidigital number, since it uses as much as digits as its factorization.

21356672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166863 (or 166851 counting only the distinct ones).

The product of its digits is 15120, while the sum is 32.

The square root of 21356672 is about 4621.3279476791. The cubic root of 21356672 is about 277.4456111788.

The spelling of 21356672 in words is "twenty-one million, three hundred fifty-six thousand, six hundred seventy-two".