21897423 has 6 divisors (see below), whose sum is σ = 31629624. Its totient is φ = 14598276.

The previous prime is 21897397. The next prime is 21897431. The reversal of 21897423 is 32479812.

It is not a de Polignac number, because 21897423 - 2⁵ = 21897391 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897433) 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, 1216515 + ... + 1216532.

It is an arithmetic number, because the mean of its divisors is an integer number (5271604).

Almost surely, 2^21897423 is an apocalyptic number.

21897423 is a deficient number, since it is larger than the sum of its proper divisors (9732201).

21897423 is a wasteful number, since it uses less digits than its factorization.

21897423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2433053 (or 2433050 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21897423 is about 4679.4682390203. The cubic root of 21897423 is about 279.7677623627.

The spelling of 21897423 in words is "twenty-one million, eight hundred ninety-seven thousand, four hundred twenty-three".