21912489 has 6 divisors (see below), whose sum is σ = 31651386. Its totient is φ = 14608320.

The previous prime is 21912461. The next prime is 21912493. The reversal of 21912489 is 98421912.

It can be written as a sum of positive squares in only one way, i.e., 17640000 + 4272489 = 4200^2 + 2067^2 .

It is not a de Polignac number, because 21912489 - 2¹³ = 21904297 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21912419) 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, 1217352 + ... + 1217369.

It is an arithmetic number, because the mean of its divisors is an integer number (5275231).

Almost surely, 2^21912489 is an apocalyptic number.

It is an amenable number.

21912489 is a deficient number, since it is larger than the sum of its proper divisors (9738897).

21912489 is a wasteful number, since it uses less digits than its factorization.

21912489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2434727 (or 2434724 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The square root of 21912489 is about 4681.0777605163. The cubic root of 21912489 is about 279.8319101668.

The spelling of 21912489 in words is "twenty-one million, nine hundred twelve thousand, four hundred eighty-nine".