21345564 has 24 divisors (see below), whose sum is σ = 51972480. Its totient is φ = 6805744.

The previous prime is 21345539. The next prime is 21345589. The reversal of 21345564 is 46554312.

It is an interprime number because it is at equal distance from previous prime (21345539) and next prime (21345589).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38394 + ... + 38945.

It is an arithmetic number, because the mean of its divisors is an integer number (2165520).

Almost surely, 2^21345564 is an apocalyptic number.

It is an amenable number.

21345564 is an abundant number, since it is smaller than the sum of its proper divisors (30626916).

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

21345564 is a wasteful number, since it uses less digits than its factorization.

21345564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77369 (or 77367 counting only the distinct ones).

The product of its digits is 14400, while the sum is 30.

The square root of 21345564 is about 4620.1259723085. The cubic root of 21345564 is about 277.3975013060.

Adding to 21345564 its reverse (46554312), we get a palindrome (67899876).

The spelling of 21345564 in words is "twenty-one million, three hundred forty-five thousand, five hundred sixty-four".