161751666820 has 24 divisors (see below), whose sum is σ = 339707703384. Its totient is φ = 64695104256.

The previous prime is 161751666779. The next prime is 161751666823. The reversal of 161751666820 is 28666157161.

It can be written as a sum of positive squares in 4 ways, for example, as 51823611904 + 109928054916 = 227648^2 + 331554^2 .

It is not an unprimeable number, because it can be changed into a prime (161751666823) 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, 105079 + ... + 578398.

It is an arithmetic number, because the mean of its divisors is an integer number (14154487641).

Almost surely, 2^161751666820 is an apocalyptic number.

161751666820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161751666820 is an abundant number, since it is smaller than the sum of its proper divisors (177956036564).

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

161751666820 is a wasteful number, since it uses less digits than its factorization.

161751666820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695319 (or 695317 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 161751666820 in words is "one hundred sixty-one billion, seven hundred fifty-one million, six hundred sixty-six thousand, eight hundred twenty".