21399718 has 4 divisors (see below), whose sum is σ = 32099580. Its totient is φ = 10699858.

The previous prime is 21399701. The next prime is 21399737. The reversal of 21399718 is 81799312.

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, 5349928 + ... + 5349931.

It is an arithmetic number, because the mean of its divisors is an integer number (8024895).

Almost surely, 2^21399718 is an apocalyptic number.

21399718 is a deficient number, since it is larger than the sum of its proper divisors (10699862).

21399718 is a wasteful number, since it uses less digits than its factorization.

21399718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10699861.

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

The square root of 21399718 is about 4625.9829225798. The cubic root of 21399718 is about 277.6318903393.

The spelling of 21399718 in words is "twenty-one million, three hundred ninety-nine thousand, seven hundred eighteen".