21327651 has 24 divisors (see below), whose sum is σ = 32529840. Its totient is φ = 13810176.

The previous prime is 21327637. The next prime is 21327653. The reversal of 21327651 is 15672312.

It is a happy number.

21327651 is a `hidden beast` number, since 2 + 1 + 3 + 2 + 7 + 651 = 666.

It is not a de Polignac number, because 21327651 - 2⁶ = 21327587 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21327653) 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 in 23 ways as a sum of consecutive naturals, for example, 36675 + ... + 37251.

It is an arithmetic number, because the mean of its divisors is an integer number (1355410).

Almost surely, 2^21327651 is an apocalyptic number.

21327651 is a deficient number, since it is larger than the sum of its proper divisors (11202189).

21327651 is an equidigital number, since it uses as much as digits as its factorization.

21327651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660 (or 617 counting only the distinct ones).

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

The square root of 21327651 is about 4618.1869819227. The cubic root of 21327651 is about 277.3198831169.

Adding to 21327651 its reverse (15672312), we get a palindrome (36999963).

The spelling of 21327651 in words is "twenty-one million, three hundred twenty-seven thousand, six hundred fifty-one".