21897315 has 48 divisors (see below), whose sum is σ = 42771456. Its totient is φ = 10267200.

The previous prime is 21897313. The next prime is 21897371. The reversal of 21897315 is 51379812.

It is not a de Polignac number, because 21897315 - 2¹ = 21897313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21897315.

It is not an unprimeable number, because it can be changed into a prime (21897313) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 14632 + ... + 16058.

It is an arithmetic number, because the mean of its divisors is an integer number (891072).

Almost surely, 2^21897315 is an apocalyptic number.

21897315 is a deficient number, since it is larger than the sum of its proper divisors (20874141).

21897315 is a wasteful number, since it uses less digits than its factorization.

21897315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1480 (or 1477 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 21897315 is about 4679.4566992334. The cubic root of 21897315 is about 279.7673024156.

The spelling of 21897315 in words is "twenty-one million, eight hundred ninety-seven thousand, three hundred fifteen".