21915699 has 16 divisors (see below), whose sum is σ = 31600800. Its totient is φ = 13430016.

The previous prime is 21915697. The next prime is 21915701. The reversal of 21915699 is 99651912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21915697) and next prime (21915701).

It is not a de Polignac number, because 21915699 - 2¹ = 21915697 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21915699.

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 15 ways as a sum of consecutive naturals, for example, 9447 + ... + 11535.

It is an arithmetic number, because the mean of its divisors is an integer number (1975050).

Almost surely, 2^21915699 is an apocalyptic number.

21915699 is a deficient number, since it is larger than the sum of its proper divisors (9685101).

21915699 is a wasteful number, since it uses less digits than its factorization.

21915699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2374.

The product of its digits is 43740, while the sum is 42.

The square root of 21915699 is about 4681.4206177185. The cubic root of 21915699 is about 279.8455738599.

The spelling of 21915699 in words is "twenty-one million, nine hundred fifteen thousand, six hundred ninety-nine".