21401264 has 30 divisors (see below), whose sum is σ = 42208236. Its totient is φ = 10512000.

The previous prime is 21401257. The next prime is 21401269. The reversal of 21401264 is 46210412.

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21401269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 85139 + ... + 85389.

Almost surely, 2^21401264 is an apocalyptic number.

It is an amenable number.

21401264 is a deficient number, since it is larger than the sum of its proper divisors (20806972).

21401264 is an equidigital number, since it uses as much as digits as its factorization.

21401264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405 (or 326 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21401264 is about 4626.1500191844. The cubic root of 21401264 is about 277.6385759191.

Adding to 21401264 its reverse (46210412), we get a palindrome (67611676).

It can be divided in two parts, 2 and 1401264, that multiplied together give a triangular number (2802528 = T₂₃₆₇).

The spelling of 21401264 in words is "twenty-one million, four hundred one thousand, two hundred sixty-four".