161906220520 has 64 divisors (see below), whose sum is σ = 397476072000. Its totient is φ = 58864634880.

The previous prime is 161906220499. The next prime is 161906220521. The reversal of 161906220520 is 25022609161.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (161906220521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2742352 + ... + 2800768.

It is an arithmetic number, because the mean of its divisors is an integer number (6210563625).

Almost surely, 2^161906220520 is an apocalyptic number.

161906220520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161906220520 is an abundant number, since it is smaller than the sum of its proper divisors (235569851480).

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

161906220520 is a wasteful number, since it uses less digits than its factorization.

161906220520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64738 (or 64734 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

Adding to 161906220520 its reverse (25022609161), we get a palindrome (186928829681).

The spelling of 161906220520 in words is "one hundred sixty-one billion, nine hundred six million, two hundred twenty thousand, five hundred twenty".