161691580 has 12 divisors (see below), whose sum is σ = 339552360. Its totient is φ = 64676624.

The previous prime is 161691557. The next prime is 161691583. The reversal of 161691580 is 85196161.

It is a super-2 number, since 2×161691580² = 52288334085792800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161691583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4042270 + ... + 4042309.

It is an arithmetic number, because the mean of its divisors is an integer number (28296030).

Almost surely, 2^161691580 is an apocalyptic number.

161691580 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161691580 is an abundant number, since it is smaller than the sum of its proper divisors (177860780).

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

161691580 is a wasteful number, since it uses less digits than its factorization.

161691580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8084588 (or 8084586 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 37.

The square root of 161691580 is about 12715.8004073672. The cubic root of 161691580 is about 544.7900097213.

The spelling of 161691580 in words is "one hundred sixty-one million, six hundred ninety-one thousand, five hundred eighty".