161821769580 has 144 divisors (see below), whose sum is σ = 521510109120. Its totient is φ = 40538340864.

The previous prime is 161821769569. The next prime is 161821769621. The reversal of 161821769580 is 85967128161.

It is a happy number.

161821769580 is a `hidden beast` number, since 1 + 618 + 2 + 17 + 6 + 9 + 5 + 8 + 0 = 666.

It is a super-2 number, since 2×161821769580² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 225784 + ... + 612063.

It is an arithmetic number, because the mean of its divisors is an integer number (3621597980).

Almost surely, 2^161821769580 is an apocalyptic number.

161821769580 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161821769580 is an abundant number, since it is smaller than the sum of its proper divisors (359688339540).

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

161821769580 is a wasteful number, since it uses less digits than its factorization.

161821769580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 837928 (or 837923 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 54.

The spelling of 161821769580 in words is "one hundred sixty-one billion, eight hundred twenty-one million, seven hundred sixty-nine thousand, five hundred eighty".