21538364 has 12 divisors (see below), whose sum is σ = 37749600. Its totient is φ = 10752768.

The previous prime is 21538339. The next prime is 21538379. The reversal of 21538364 is 46383512.

It is a super-2 number, since 2×21538364² = 927802247592992, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21538364.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 869 + ... + 6620.

It is an arithmetic number, because the mean of its divisors is an integer number (3145800).

Almost surely, 2^21538364 is an apocalyptic number.

It is an amenable number.

21538364 is a deficient number, since it is larger than the sum of its proper divisors (16211236).

21538364 is a wasteful number, since it uses less digits than its factorization.

21538364 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8212 (or 8210 counting only the distinct ones).

The product of its digits is 17280, while the sum is 32.

The square root of 21538364 is about 4640.9443004630. The cubic root of 21538364 is about 278.2301804597.

The spelling of 21538364 in words is "twenty-one million, five hundred thirty-eight thousand, three hundred sixty-four".