161396781 has 32 divisors (see below), whose sum is σ = 266289408. Its totient is φ = 84672000.

The previous prime is 161396699. The next prime is 161396821. The reversal of 161396781 is 187693161.

It is not a de Polignac number, because 161396781 - 2⁹ = 161396269 is a prime.

It is a super-2 number, since 2×161396781² = 52097841834323922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161396381) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52281 + ... + 55281.

It is an arithmetic number, because the mean of its divisors is an integer number (8321544).

Almost surely, 2^161396781 is an apocalyptic number.

It is an amenable number.

161396781 is a deficient number, since it is larger than the sum of its proper divisors (104892627).

161396781 is a wasteful number, since it uses less digits than its factorization.

161396781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3221.

The product of its digits is 54432, while the sum is 42.

The square root of 161396781 is about 12704.2032808043. The cubic root of 161396781 is about 544.4587179823.

The spelling of 161396781 in words is "one hundred sixty-one million, three hundred ninety-six thousand, seven hundred eighty-one".