21924397 has 4 divisors (see below), whose sum is σ = 23917536. Its totient is φ = 19931260.

The previous prime is 21924389. The next prime is 21924401. The reversal of 21924397 is 79342912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21924397 - 2³ = 21924389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21924337) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 996553 + ... + 996574.

It is an arithmetic number, because the mean of its divisors is an integer number (5979384).

Almost surely, 2^21924397 is an apocalyptic number.

It is an amenable number.

21924397 is a deficient number, since it is larger than the sum of its proper divisors (1993139).

21924397 is a wasteful number, since it uses less digits than its factorization.

21924397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1993138.

The product of its digits is 27216, while the sum is 37.

The square root of 21924397 is about 4682.3495170694. The cubic root of 21924397 is about 279.8825910814.

The spelling of 21924397 in words is "twenty-one million, nine hundred twenty-four thousand, three hundred ninety-seven".