21915693 has 6 divisors (see below), whose sum is σ = 31656014. Its totient is φ = 14610456.

The previous prime is 21915679. The next prime is 21915697. The reversal of 21915693 is 39651912.

21915693 is a `hidden beast` number, since 2 + 1 + 91 + 569 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 14722569 + 7193124 = 3837^2 + 2682^2 .

It is not a de Polignac number, because 21915693 - 2⁶ = 21915629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21915697) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1217530 + ... + 1217547.

Almost surely, 2^21915693 is an apocalyptic number.

It is an amenable number.

21915693 is a deficient number, since it is larger than the sum of its proper divisors (9740321).

21915693 is a wasteful number, since it uses less digits than its factorization.

21915693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2435083 (or 2435080 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 21915693 is about 4681.4199768874. The cubic root of 21915693 is about 279.8455483215.

The spelling of 21915693 in words is "twenty-one million, nine hundred fifteen thousand, six hundred ninety-three".