21158117279 has 16 divisors (see below), whose sum is σ = 23894304000. Its totient is φ = 18598761216.

The previous prime is 21158117231. The next prime is 21158117311. The reversal of 21158117279 is 97271185112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21158117279 - 2¹² = 21158113183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158117479) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 356879 + ... + 411920.

It is an arithmetic number, because the mean of its divisors is an integer number (1493394000).

Almost surely, 2^21158117279 is an apocalyptic number.

21158117279 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21158117279 is a deficient number, since it is larger than the sum of its proper divisors (2736186721).

21158117279 is a wasteful number, since it uses less digits than its factorization.

21158117279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768914.

The product of its digits is 70560, while the sum is 44.

The spelling of 21158117279 in words is "twenty-one billion, one hundred fifty-eight million, one hundred seventeen thousand, two hundred seventy-nine".