20721264 has 20 divisors (see below), whose sum is σ = 53530056. Its totient is φ = 6907072.

The previous prime is 20721263. The next prime is 20721271. The reversal of 20721264 is 46212702.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721263) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 215799 + ... + 215894.

Almost surely, 2^20721264 is an apocalyptic number.

20721264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

20721264 is an abundant number, since it is smaller than the sum of its proper divisors (32808792).

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

20721264 is a wasteful number, since it uses less digits than its factorization.

20721264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431704 (or 431698 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 20721264 is about 4552.0615110080. The cubic root of 20721264 is about 274.6663236661. Note that the first 3 decimals are identical.

Adding to 20721264 its reverse (46212702), we get a palindrome (66933966).

The spelling of 20721264 in words is "twenty million, seven hundred twenty-one thousand, two hundred sixty-four".