161199897021 has 24 divisors (see below), whose sum is σ = 238610211840. Its totient is φ = 104821017696.

The previous prime is 161199897007. The next prime is 161199897077. The reversal of 161199897021 is 120798991161.

It is not a de Polignac number, because 161199897021 - 2¹⁴ = 161199880637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161199897091) 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, 526381 + ... + 774258.

It is an arithmetic number, because the mean of its divisors is an integer number (9942092160).

Almost surely, 2^161199897021 is an apocalyptic number.

It is an amenable number.

161199897021 is a deficient number, since it is larger than the sum of its proper divisors (77410314819).

161199897021 is a wasteful number, since it uses less digits than its factorization.

161199897021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1300985 (or 1300982 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 54.

The spelling of 161199897021 in words is "one hundred sixty-one billion, one hundred ninety-nine million, eight hundred ninety-seven thousand, twenty-one".