161215645 has 4 divisors (see below), whose sum is σ = 193458780. Its totient is φ = 128972512.

The previous prime is 161215577. The next prime is 161215657. The reversal of 161215645 is 546512161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 93663684 + 67551961 = 9678^2 + 8219^2 .

It is a cyclic number.

It is not a de Polignac number, because 161215645 - 2⁷ = 161215517 is a prime.

It is a Smith number, since the sum of its digits (31) 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 (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16121560 + ... + 16121569.

It is an arithmetic number, because the mean of its divisors is an integer number (48364695).

Almost surely, 2^161215645 is an apocalyptic number.

It is an amenable number.

161215645 is a deficient number, since it is larger than the sum of its proper divisors (32243135).

161215645 is an equidigital number, since it uses as much as digits as its factorization.

161215645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32243134.

The product of its digits is 7200, while the sum is 31.

The square root of 161215645 is about 12697.0723003376. The cubic root of 161215645 is about 544.2549592891.

The spelling of 161215645 in words is "one hundred sixty-one million, two hundred fifteen thousand, six hundred forty-five".