21513475 has 12 divisors (see below), whose sum is σ = 26884440. Its totient is φ = 17076800.

The previous prime is 21513469. The next prime is 21513511. The reversal of 21513475 is 57431512.

It is a happy number.

It is not a de Polignac number, because 21513475 - 2³ = 21513467 is a prime.

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, 10 + ... + 6559.

It is an arithmetic number, because the mean of its divisors is an integer number (2240370).

Almost surely, 2^21513475 is an apocalyptic number.

21513475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21513475 is a deficient number, since it is larger than the sum of its proper divisors (5370965).

21513475 is a wasteful number, since it uses less digits than its factorization.

21513475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6710 (or 6705 counting only the distinct ones).

The product of its digits is 4200, while the sum is 28.

The square root of 21513475 is about 4638.2620667660. The cubic root of 21513475 is about 278.1229680447.

Adding to 21513475 its reverse (57431512), we get a palindrome (78944987).

The spelling of 21513475 in words is "twenty-one million, five hundred thirteen thousand, four hundred seventy-five".