21732651 has 8 divisors (see below), whose sum is σ = 32196560. Its totient is φ = 14488416.

The previous prime is 21732593. The next prime is 21732661. The reversal of 21732651 is 15623712.

It is a happy number.

21732651 is a `hidden beast` number, since 2 + 1 + 7 + 3 + 2 + 651 = 666.

It is not a de Polignac number, because 21732651 - 2¹⁵ = 21699883 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 804913 = 21732651 / (2 + 1 + 7 + 3 + 2 + 6 + 5 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21732661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 402430 + ... + 402483.

It is an arithmetic number, because the mean of its divisors is an integer number (4024570).

Almost surely, 2^21732651 is an apocalyptic number.

21732651 is a deficient number, since it is larger than the sum of its proper divisors (10463909).

21732651 is an equidigital number, since it uses as much as digits as its factorization.

21732651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804922 (or 804916 counting only the distinct ones).

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

The square root of 21732651 is about 4661.8291474485. The cubic root of 21732651 is about 279.0642700821.

The spelling of 21732651 in words is "twenty-one million, seven hundred thirty-two thousand, six hundred fifty-one".