161693990 has 32 divisors (see below), whose sum is σ = 312167520. Its totient is φ = 60113664.

The previous prime is 161693989. The next prime is 161694007. The reversal of 161693990 is 99396161.

It is a happy number.

It is a super-2 number, since 2×161693990² = 52289892804240200, which contains 22 as substring.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2042 + ... + 18098.

It is an arithmetic number, because the mean of its divisors is an integer number (9755235).

Almost surely, 2^161693990 is an apocalyptic number.

161693990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

161693990 is a deficient number, since it is larger than the sum of its proper divisors (150473530).

161693990 is a wasteful number, since it uses less digits than its factorization.

161693990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16136.

The product of its (nonzero) digits is 78732, while the sum is 44.

The square root of 161693990 is about 12715.8951710055. The cubic root of 161693990 is about 544.7927163916.

The spelling of 161693990 in words is "one hundred sixty-one million, six hundred ninety-three thousand, nine hundred ninety".