161516781 has 16 divisors (see below), whose sum is σ = 239557120. Its totient is φ = 107555040.

The previous prime is 161516767. The next prime is 161516791. The reversal of 161516781 is 187615161.

161516781 is a `hidden beast` number, since 1 + 61 + 516 + 7 + 81 = 666.

It is not a de Polignac number, because 161516781 - 2⁶ = 161516717 is a prime.

It is a super-2 number, since 2×161516781² = 52175341089203922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161516731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24996 + ... + 30786.

It is an arithmetic number, because the mean of its divisors is an integer number (14972320).

Almost surely, 2^161516781 is an apocalyptic number.

It is an amenable number.

161516781 is a deficient number, since it is larger than the sum of its proper divisors (78040339).

161516781 is a wasteful number, since it uses less digits than its factorization.

161516781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6833 (or 6827 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The square root of 161516781 is about 12708.9252496031. The cubic root of 161516781 is about 544.5936212521.

The spelling of 161516781 in words is "one hundred sixty-one million, five hundred sixteen thousand, seven hundred eighty-one".