161665574 has 48 divisors (see below), whose sum is σ = 294319872. Its totient is φ = 65225424.

The previous prime is 161665561. The next prime is 161665579. The reversal of 161665574 is 475566161.

It is a super-2 number, since 2×161665574² = 52271515633498952, which contains 22 as substring.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

Its product of digits (151200) is a multiple of the sum of its prime divisors (378).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161665579) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 614567 + ... + 614829.

It is an arithmetic number, because the mean of its divisors is an integer number (6131664).

Almost surely, 2^161665574 is an apocalyptic number.

161665574 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

161665574 is a deficient number, since it is larger than the sum of its proper divisors (132654298).

161665574 is a wasteful number, since it uses less digits than its factorization.

161665574 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401 (or 378 counting only the distinct ones).

The product of its digits is 151200, while the sum is 41.

The square root of 161665574 is about 12714.7777802052. Note that the first 4 decimals coincide. The cubic root of 161665574 is about 544.7608006790.

The spelling of 161665574 in words is "one hundred sixty-one million, six hundred sixty-five thousand, five hundred seventy-four".