161639980 has 24 divisors (see below), whose sum is σ = 340094160. Its totient is φ = 64532160.

The previous prime is 161639977. The next prime is 161639981. The reversal of 161639980 is 89936161.

It is a super-2 number, since 2×161639980² = 52254966268800800, which contains 22 as substring.

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (161639981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3351 + ... + 18289.

It is an arithmetic number, because the mean of its divisors is an integer number (14170590).

Almost surely, 2^161639980 is an apocalyptic number.

161639980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161639980 is an abundant number, since it is smaller than the sum of its proper divisors (178454180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161639980 is a wasteful number, since it uses less digits than its factorization.

161639980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15489 (or 15487 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 43.

The square root of 161639980 is about 12713.7712737016. The cubic root of 161639980 is about 544.7320513222.

The spelling of 161639980 in words is "one hundred sixty-one million, six hundred thirty-nine thousand, nine hundred eighty".