21264039 has 10 divisors (see below), whose sum is σ = 31764920. Its totient is φ = 14175972.

The previous prime is 21264037. The next prime is 21264053. The reversal of 21264039 is 93046212.

21264039 is a `hidden beast` number, since 2 + 12 + 640 + 3 + 9 = 666.

It is not a de Polignac number, because 21264039 - 2¹ = 21264037 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264031) 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 9 ways as a sum of consecutive naturals, for example, 131179 + ... + 131340.

It is an arithmetic number, because the mean of its divisors is an integer number (3176492).

Almost surely, 2^21264039 is an apocalyptic number.

21264039 is a deficient number, since it is larger than the sum of its proper divisors (10500881).

21264039 is an equidigital number, since it uses as much as digits as its factorization.

21264039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262531 (or 262522 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21264039 is about 4611.2947205747. The cubic root of 21264039 is about 277.0438964783.

The spelling of 21264039 in words is "twenty-one million, two hundred sixty-four thousand, thirty-nine".