21897425 has 12 divisors (see below), whose sum is σ = 29621616. Its totient is φ = 15925200.

The previous prime is 21897397. The next prime is 21897431. The reversal of 21897425 is 52479812.

It is not a de Polignac number, because 21897425 - 2¹⁰ = 21896401 is a prime.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39539 + ... + 40088.

It is an arithmetic number, because the mean of its divisors is an integer number (2468468).

Almost surely, 2^21897425 is an apocalyptic number.

21897425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21897425 is a deficient number, since it is larger than the sum of its proper divisors (7724191).

21897425 is a wasteful number, since it uses less digits than its factorization.

21897425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79648 (or 79643 counting only the distinct ones).

The product of its digits is 40320, while the sum is 38.

The square root of 21897425 is about 4679.4684527198. The cubic root of 21897425 is about 279.7677708802.

It can be divided in two parts, 21897 and 425, that added together give a palindrome (22322).

The spelling of 21897425 in words is "twenty-one million, eight hundred ninety-seven thousand, four hundred twenty-five".