21156501699 has 12 divisors (see below), whose sum is σ = 31691221016. Its totient is φ = 14104334304.

The previous prime is 21156501697. The next prime is 21156501719. The reversal of 21156501699 is 99610565112.

It is a happy number.

21156501699 is a `hidden beast` number, since 2 + 1 + 1 + 56 + 501 + 6 + 99 = 666.

It is not a de Polignac number, because 21156501699 - 2¹ = 21156501697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21156501697) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43531654 + ... + 43532139.

Almost surely, 2^21156501699 is an apocalyptic number.

21156501699 is a deficient number, since it is larger than the sum of its proper divisors (10534719317).

21156501699 is an frugal number, since it uses more digits than its factorization.

21156501699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87063808 (or 87063796 counting only the distinct ones).

The product of its (nonzero) digits is 145800, while the sum is 45.

The spelling of 21156501699 in words is "twenty-one billion, one hundred fifty-six million, five hundred one thousand, six hundred ninety-nine".