161561000051 has 8 divisors (see below), whose sum is σ = 185524593600. Its totient is φ = 139143444840.

The previous prime is 161561000047. The next prime is 161561000057. The reversal of 161561000051 is 150000165161.

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

It is a cyclic number.

It is not a de Polignac number, because 161561000051 - 2² = 161561000047 is a prime.

It is a super-2 number, since 2×161561000051² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161561000057) 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, 386509361 + ... + 386509778.

It is an arithmetic number, because the mean of its divisors is an integer number (23190574200).

Almost surely, 2^161561000051 is an apocalyptic number.

161561000051 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

161561000051 is a deficient number, since it is larger than the sum of its proper divisors (23963593549).

161561000051 is a wasteful number, since it uses less digits than its factorization.

161561000051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 773019169.

The product of its (nonzero) digits is 900, while the sum is 26.

The spelling of 161561000051 in words is "one hundred sixty-one billion, five hundred sixty-one million, fifty-one", and thus it is an aban number.