161561399 has 8 divisors (see below), whose sum is σ = 164904960. Its totient is φ = 158250456.

The previous prime is 161561381. The next prime is 161561417. The reversal of 161561399 is 993165161.

It is an interprime number because it is at equal distance from previous prime (161561381) and next prime (161561417).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161561399 is a prime.

It is a super-2 number, since 2×161561399² = 52204171293674402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161561359) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1982 + ... + 18084.

It is an arithmetic number, because the mean of its divisors is an integer number (20613120).

Almost surely, 2^161561399 is an apocalyptic number.

161561399 is a deficient number, since it is larger than the sum of its proper divisors (3343561).

161561399 is a wasteful number, since it uses less digits than its factorization.

161561399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16309.

The product of its digits is 43740, while the sum is 41.

The square root of 161561399 is about 12710.6805089263. The cubic root of 161561399 is about 544.6437634951.

The spelling of 161561399 in words is "one hundred sixty-one million, five hundred sixty-one thousand, three hundred ninety-nine".