161921204872 has 32 divisors (see below), whose sum is σ = 347183608320. Its totient is φ = 69352882560.

The previous prime is 161921204821. The next prime is 161921204873. The reversal of 161921204872 is 278402129161.

It is a super-3 number, since 3×161921204872³ (a number of 35 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (161921204873) 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, 779704 + ... + 965287.

It is an arithmetic number, because the mean of its divisors is an integer number (10849487760).

Almost surely, 2^161921204872 is an apocalyptic number.

It is an amenable number.

161921204872 is an abundant number, since it is smaller than the sum of its proper divisors (185262403448).

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

161921204872 is a wasteful number, since it uses less digits than its factorization.

161921204872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1746661 (or 1746657 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 43.

The spelling of 161921204872 in words is "one hundred sixty-one billion, nine hundred twenty-one million, two hundred four thousand, eight hundred seventy-two".