21912297 has 8 divisors (see below), whose sum is σ = 31872480. Its totient is φ = 13280160.

The previous prime is 21912287. The next prime is 21912311. The reversal of 21912297 is 79221912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21912297 - 2⁴ = 21912281 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 664009 = 21912297 / (2 + 1 + 9 + 1 + 2 + 2 + 9 + 7).

It is not an unprimeable number, because it can be changed into a prime (21912217) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 331972 + ... + 332037.

It is an arithmetic number, because the mean of its divisors is an integer number (3984060).

Almost surely, 2^21912297 is an apocalyptic number.

It is an amenable number.

21912297 is a deficient number, since it is larger than the sum of its proper divisors (9960183).

21912297 is a wasteful number, since it uses less digits than its factorization.

21912297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 664023.

The product of its digits is 4536, while the sum is 33.

The square root of 21912297 is about 4681.0572523737. The cubic root of 21912297 is about 279.8310928569.

The spelling of 21912297 in words is "twenty-one million, nine hundred twelve thousand, two hundred ninety-seven".