21397886 has 8 divisors (see below), whose sum is σ = 32122200. Its totient is φ = 10690488.

The previous prime is 21397879. The next prime is 21397907. The reversal of 21397886 is 68879312.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 356 + ... + 6551.

It is an arithmetic number, because the mean of its divisors is an integer number (4015275).

Almost surely, 2^21397886 is an apocalyptic number.

21397886 is a deficient number, since it is larger than the sum of its proper divisors (10724314).

21397886 is a wasteful number, since it uses less digits than its factorization.

21397886 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8458.

The product of its digits is 145152, while the sum is 44.

The square root of 21397886 is about 4625.7849063699. The cubic root of 21397886 is about 277.6239675536.

The spelling of 21397886 in words is "twenty-one million, three hundred ninety-seven thousand, eight hundred eighty-six".