999999999999956 has 12 divisors (see below), whose sum is σ = 1750003382479968. Its totient is φ = 499999033577112.

The previous prime is 999999999999947. The next prime is 999999999999989. The reversal of 999999999999956 is 659999999999999.

It is a happy number.

It is a super-9 number, since 9×999999999999956⁹ (a number of 136 digits) contains 999999999 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 239275046 + ... + 243418461.

It is an arithmetic number, because the mean of its divisors is an integer number (145833615206664).

Almost surely, 2^{999999999999956} is an apocalyptic number.

It is an amenable number.

999999999999956 is a deficient number, since it is larger than the sum of its proper divisors (750003382480012).

999999999999956 is a wasteful number, since it uses less digits than its factorization.

999999999999956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 483211438 (or 483211436 counting only the distinct ones).

The product of its digits is 76255974849870, while the sum is 128.

It can be divided in two parts, 99999999999995 and 6, that added together give a palindrome (100000000000001).

The spelling of 999999999999956 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred fifty-six".