21167255918 has 4 divisors (see below), whose sum is σ = 31750883880. Its totient is φ = 10583627958.

The previous prime is 21167255903. The next prime is 21167255939. The reversal of 21167255918 is 81955276112.

It is a happy number.

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, 5291813978 + ... + 5291813981.

It is an arithmetic number, because the mean of its divisors is an integer number (7937720970).

Almost surely, 2^21167255918 is an apocalyptic number.

21167255918 is a deficient number, since it is larger than the sum of its proper divisors (10583627962).

21167255918 is a wasteful number, since it uses less digits than its factorization.

21167255918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10583627961.

The product of its digits is 302400, while the sum is 47.

The spelling of 21167255918 in words is "twenty-one billion, one hundred sixty-seven million, two hundred fifty-five thousand, nine hundred eighteen".