21172672 has 14 divisors (see below), whose sum is σ = 42014648. Its totient is φ = 10586304.

The previous prime is 21172663. The next prime is 21172691. The reversal of 21172672 is 27627112.

It is a self number, because there is not a number n which added to its sum of digits gives 21172672.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165348 + ... + 165475.

Almost surely, 2^21172672 is an apocalyptic number.

It is an amenable number.

21172672 is a deficient number, since it is larger than the sum of its proper divisors (20841976).

21172672 is an equidigital number, since it uses as much as digits as its factorization.

21172672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330835 (or 330825 counting only the distinct ones).

The product of its digits is 2352, while the sum is 28.

The square root of 21172672 is about 4601.3771851479. The cubic root of 21172672 is about 276.6465274610.

Adding to 21172672 its reverse (27627112), we get a palindrome (48799784).

The spelling of 21172672 in words is "twenty-one million, one hundred seventy-two thousand, six hundred seventy-two".