161972022780 has 144 divisors (see below), whose sum is σ = 514938138624. Its totient is φ = 41132361600.

The previous prime is 161972022767. The next prime is 161972022787. The reversal of 161972022780 is 87220279161.

It is a happy number.

161972022780 is a `hidden beast` number, since 1 + 619 + 7 + 2 + 0 + 2 + 27 + 8 + 0 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161972022787) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 853605 + ... + 1025955.

It is an arithmetic number, because the mean of its divisors is an integer number (3575959296).

Almost surely, 2^161972022780 is an apocalyptic number.

161972022780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161972022780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (257469069312).

161972022780 is an abundant number, since it is smaller than the sum of its proper divisors (352966115844).

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

161972022780 is a wasteful number, since it uses less digits than its factorization.

161972022780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172616 (or 172611 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 45.

The spelling of 161972022780 in words is "one hundred sixty-one billion, nine hundred seventy-two million, twenty-two thousand, seven hundred eighty".