161636993986 has 8 divisors (see below), whose sum is σ = 261105913404. Its totient is φ = 74601689520.

The previous prime is 161636993923. The next prime is 161636994017. The reversal of 161636993986 is 689399636161.

It can be written as a sum of positive squares in 2 ways, for example, as 147125177761 + 14511816225 = 383569^2 + 120465^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×161636993986² (a number of 23 digits) contains 22 as substring.

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, 3108403705 + ... + 3108403756.

Almost surely, 2^161636993986 is an apocalyptic number.

161636993986 is a deficient number, since it is larger than the sum of its proper divisors (99468919418).

161636993986 is a wasteful number, since it uses less digits than its factorization.

161636993986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6216807476.

The product of its digits is 68024448, while the sum is 67.

The spelling of 161636993986 in words is "one hundred sixty-one billion, six hundred thirty-six million, nine hundred ninety-three thousand, nine hundred eighty-six".