21372651 has 12 divisors (see below), whose sum is σ = 30911712. Its totient is φ = 14229936.

The previous prime is 21372649. The next prime is 21372653. The reversal of 21372651 is 15627312.

It is a happy number.

21372651 is a `hidden beast` number, since 2 + 1 + 3 + 7 + 2 + 651 = 666.

It is an interprime number because it is at equal distance from previous prime (21372649) and next prime (21372653).

It is not a de Polignac number, because 21372651 - 2¹ = 21372649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21372653) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12585 + ... + 14181.

It is an arithmetic number, because the mean of its divisors is an integer number (2575976).

Almost surely, 2^21372651 is an apocalyptic number.

21372651 is a deficient number, since it is larger than the sum of its proper divisors (9539061).

21372651 is a wasteful number, since it uses less digits than its factorization.

21372651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3090 (or 3087 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21372651 is about 4623.0564565015. The cubic root of 21372651 is about 277.5147885958.

Adding to 21372651 its reverse (15627312), we get a palindrome (36999963).

The spelling of 21372651 in words is "twenty-one million, three hundred seventy-two thousand, six hundred fifty-one".