161666569890 has 48 divisors (see below), whose sum is σ = 480380666688. Its totient is φ = 36952358688.

The previous prime is 161666569879. The next prime is 161666569921. The reversal of 161666569890 is 98965666161.

It is a super-2 number, since 2×161666569890² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 128306172 + ... + 128307431.

It is an arithmetic number, because the mean of its divisors is an integer number (10007930556).

Almost surely, 2^161666569890 is an apocalyptic number.

161666569890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

161666569890 is an abundant number, since it is smaller than the sum of its proper divisors (318714096798).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161666569890 is a wasteful number, since it uses less digits than its factorization.

161666569890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256613623 (or 256613620 counting only the distinct ones).

The product of its (nonzero) digits is 25194240, while the sum is 63.

The spelling of 161666569890 in words is "one hundred sixty-one billion, six hundred sixty-six million, five hundred sixty-nine thousand, eight hundred ninety".