21938897 has 4 divisors (see below), whose sum is σ = 22152000. Its totient is φ = 21725796.

The previous prime is 21938881. The next prime is 21938899. The reversal of 21938897 is 79883912.

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 21938897 - 2⁴ = 21938881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21938899) 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, 106397 + ... + 106602.

It is an arithmetic number, because the mean of its divisors is an integer number (5538000).

Almost surely, 2^21938897 is an apocalyptic number.

It is an amenable number.

21938897 is a deficient number, since it is larger than the sum of its proper divisors (213103).

21938897 is a wasteful number, since it uses less digits than its factorization.

21938897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213102.

The product of its digits is 217728, while the sum is 47.

The square root of 21938897 is about 4683.8976291119. The cubic root of 21938897 is about 279.9442788780.

The spelling of 21938897 in words is "twenty-one million, nine hundred thirty-eight thousand, eight hundred ninety-seven".