161681688986 has 8 divisors (see below), whose sum is σ = 249077196660. Its totient is φ = 78655956768.

The previous prime is 161681688983. The next prime is 161681689009. The reversal of 161681688986 is 689886186161.

It can be written as a sum of positive squares in 2 ways, for example, as 127221335761 + 34460353225 = 356681^2 + 185635^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×161681688986² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161681688983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1092443771 + ... + 1092443918.

Almost surely, 2^161681688986 is an apocalyptic number.

161681688986 is a deficient number, since it is larger than the sum of its proper divisors (87395507674).

161681688986 is a wasteful number, since it uses less digits than its factorization.

161681688986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2184887728.

The product of its digits is 47775744, while the sum is 68.

The spelling of 161681688986 in words is "one hundred sixty-one billion, six hundred eighty-one million, six hundred eighty-eight thousand, nine hundred eighty-six".