21931897 has 8 divisors (see below), whose sum is σ = 23841216. Its totient is φ = 20054352.

The previous prime is 21931891. The next prime is 21931913. The reversal of 21931897 is 79813912.

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

It is a cyclic number.

It is not a de Polignac number, because 21931897 - 2¹¹ = 21929849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21931891) 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, 6493 + ... + 9274.

It is an arithmetic number, because the mean of its divisors is an integer number (2980152).

Almost surely, 2^21931897 is an apocalyptic number.

It is an amenable number.

21931897 is a deficient number, since it is larger than the sum of its proper divisors (1909319).

21931897 is a wasteful number, since it uses less digits than its factorization.

21931897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15887.

The product of its digits is 27216, while the sum is 40.

The square root of 21931897 is about 4683.1503285716. The cubic root of 21931897 is about 279.9145019570.

The spelling of 21931897 in words is "twenty-one million, nine hundred thirty-one thousand, eight hundred ninety-seven".