161993137481 has 16 divisors (see below), whose sum is σ = 189720541824. Its totient is φ = 135421663104.

The previous prime is 161993137469. The next prime is 161993137489. The reversal of 161993137481 is 184731399161.

It is a de Polignac number, because none of the positive numbers 2^k-161993137481 is a prime.

It is a super-2 number, since 2×161993137481² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161993137489) 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, 193700 + ... + 601253.

It is an arithmetic number, because the mean of its divisors is an integer number (11857533864).

Almost surely, 2^161993137481 is an apocalyptic number.

It is an amenable number.

161993137481 is a deficient number, since it is larger than the sum of its proper divisors (27727404343).

161993137481 is an equidigital number, since it uses as much as digits as its factorization.

161993137481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 795680.

The product of its digits is 979776, while the sum is 53.

The spelling of 161993137481 in words is "one hundred sixty-one billion, nine hundred ninety-three million, one hundred thirty-seven thousand, four hundred eighty-one".