21918958 has 4 divisors (see below), whose sum is σ = 32878440. Its totient is φ = 10959478.

The previous prime is 21918881. The next prime is 21919003. The reversal of 21918958 is 85981912.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5479738 + ... + 5479741.

It is an arithmetic number, because the mean of its divisors is an integer number (8219610).

Almost surely, 2^21918958 is an apocalyptic number.

21918958 is a deficient number, since it is larger than the sum of its proper divisors (10959482).

21918958 is a wasteful number, since it uses less digits than its factorization.

21918958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10959481.

The product of its digits is 51840, while the sum is 43.

The square root of 21918958 is about 4681.7686828804. The cubic root of 21918958 is about 279.8594447616.

The spelling of 21918958 in words is "twenty-one million, nine hundred eighteen thousand, nine hundred fifty-eight".