21501264 has 20 divisors (see below), whose sum is σ = 55545056. Its totient is φ = 7167072.

The previous prime is 21501253. The next prime is 21501281. The reversal of 21501264 is 46210512.

It is a self number, because there is not a number n which added to its sum of digits gives 21501264.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 223924 + ... + 224019.

Almost surely, 2^21501264 is an apocalyptic number.

21501264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21501264 is an abundant number, since it is smaller than the sum of its proper divisors (34043792).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21501264 is a wasteful number, since it uses less digits than its factorization.

21501264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447954 (or 447948 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21501264 is about 4636.9455463699. The cubic root of 21501264 is about 278.0703374289.

Adding to 21501264 its reverse (46210512), we get a palindrome (67711776).

The spelling of 21501264 in words is "twenty-one million, five hundred one thousand, two hundred sixty-four".