21513118 has 16 divisors (see below), whose sum is σ = 35279856. Its totient is φ = 9757440.

The previous prime is 21513113. The next prime is 21513127. The reversal of 21513118 is 81131512.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513113) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 14080 + ... + 15532.

It is an arithmetic number, because the mean of its divisors is an integer number (2204991).

Almost surely, 2^21513118 is an apocalyptic number.

21513118 is a deficient number, since it is larger than the sum of its proper divisors (13766738).

21513118 is a wasteful number, since it uses less digits than its factorization.

21513118 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2139.

The product of its digits is 240, while the sum is 22.

The square root of 21513118 is about 4638.2235823643. The cubic root of 21513118 is about 278.1214296221.

The spelling of 21513118 in words is "twenty-one million, five hundred thirteen thousand, one hundred eighteen".