161921890520 has 32 divisors (see below), whose sum is σ = 392349197520. Its totient is φ = 59786544000.

The previous prime is 161921890519. The next prime is 161921890541. The reversal of 161921890520 is 25098129161.

It is a super-3 number, since 3×161921890520³ (a number of 35 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 155693606 + ... + 155694645.

Almost surely, 2^161921890520 is an apocalyptic number.

161921890520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161921890520 is an abundant number, since it is smaller than the sum of its proper divisors (230427307000).

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

161921890520 is a wasteful number, since it uses less digits than its factorization.

161921890520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311388275 (or 311388271 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 44.

The spelling of 161921890520 in words is "one hundred sixty-one billion, nine hundred twenty-one million, eight hundred ninety thousand, five hundred twenty".