21511364 has 12 divisors (see below), whose sum is σ = 43022784. Its totient is φ = 9219144.

The previous prime is 21511361. The next prime is 21511381. The reversal of 21511364 is 46311512.

21511364 is an admirable number.

It is a super-2 number, since 2×21511364² = 925477562280992, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21511361) 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, 384104 + ... + 384159.

It is an arithmetic number, because the mean of its divisors is an integer number (3585232).

Almost surely, 2^21511364 is an apocalyptic number.

It is an amenable number.

21511364 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21511364 is a wasteful number, since it uses less digits than its factorization.

21511364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768274 (or 768272 counting only the distinct ones).

The product of its digits is 720, while the sum is 23.

The square root of 21511364 is about 4638.0344975000. The cubic root of 21511364 is about 278.1138708504.

Adding to 21511364 its reverse (46311512), we get a palindrome (67822876).

The spelling of 21511364 in words is "twenty-one million, five hundred eleven thousand, three hundred sixty-four".