21513717 has 24 divisors (see below), whose sum is σ = 33194304. Its totient is φ = 13394304.

The previous prime is 21513697. The next prime is 21513749. The reversal of 21513717 is 71731512.

It is a happy number.

It is not a de Polignac number, because 21513717 - 2²³ = 13125109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513787) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7693 + ... + 10109.

It is an arithmetic number, because the mean of its divisors is an integer number (1383096).

Almost surely, 2^21513717 is an apocalyptic number.

It is an amenable number.

21513717 is a deficient number, since it is larger than the sum of its proper divisors (11680587).

21513717 is a wasteful number, since it uses less digits than its factorization.

21513717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2489 (or 2486 counting only the distinct ones).

The product of its digits is 1470, while the sum is 27.

The square root of 21513717 is about 4638.2881540499. The cubic root of 21513717 is about 278.1240108874.

The spelling of 21513717 in words is "twenty-one million, five hundred thirteen thousand, seven hundred seventeen".