161635645 has 4 divisors (see below), whose sum is σ = 193962780. Its totient is φ = 129308512.

The previous prime is 161635631. The next prime is 161635657. The reversal of 161635645 is 546536161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 546536161 = 311 ⋅1757351.

It can be written as a sum of positive squares in 2 ways, for example, as 62394201 + 99241444 = 7899^2 + 9962^2 .

It is a cyclic number.

It is not a de Polignac number, because 161635645 - 2⁵ = 161635613 is a prime.

It is a super-2 number, since 2×161635645² = 52252163469132050, which contains 22 as substring.

It is a congruent number.

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, 16163560 + ... + 16163569.

It is an arithmetic number, because the mean of its divisors is an integer number (48490695).

Almost surely, 2^161635645 is an apocalyptic number.

It is an amenable number.

161635645 is a deficient number, since it is larger than the sum of its proper divisors (32327135).

161635645 is an equidigital number, since it uses as much as digits as its factorization.

161635645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32327134.

The product of its digits is 64800, while the sum is 37.

The square root of 161635645 is about 12713.6007881324. The cubic root of 161635645 is about 544.7271815812.

The spelling of 161635645 in words is "one hundred sixty-one million, six hundred thirty-five thousand, six hundred forty-five".