21513372 has 36 divisors (see below), whose sum is σ = 52490760. Its totient is φ = 6857312.

The previous prime is 21513361. The next prime is 21513383. The reversal of 21513372 is 27331512.

It is an interprime number because it is at equal distance from previous prime (21513361) and next prime (21513383).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4654 + ... + 8042.

Almost surely, 2^21513372 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21513372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26245380).

21513372 is an abundant number, since it is smaller than the sum of its proper divisors (30977388).

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

21513372 is a wasteful number, since it uses less digits than its factorization.

21513372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3442 (or 3417 counting only the distinct ones).

The product of its digits is 1260, while the sum is 24.

The square root of 21513372 is about 4638.2509634559. The cubic root of 21513372 is about 278.1225241879.

Adding to 21513372 its reverse (27331512), we get a palindrome (48844884).

The spelling of 21513372 in words is "twenty-one million, five hundred thirteen thousand, three hundred seventy-two".