161057781 has 32 divisors (see below), whose sum is σ = 246385920. Its totient is φ = 103902912.

The previous prime is 161057773. The next prime is 161057789. The reversal of 161057781 is 187750161.

It is a happy number.

161057781 is a `hidden beast` number, since 1 + 6 + 1 + 0 + 577 + 81 = 666.

It is an interprime number because it is at equal distance from previous prime (161057773) and next prime (161057789).

It is not a de Polignac number, because 161057781 - 2³ = 161057773 is a prime.

It is a super-3 number, since 3×161057781³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161057789) 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, 262431 + ... + 263043.

It is an arithmetic number, because the mean of its divisors is an integer number (7699560).

Almost surely, 2^161057781 is an apocalyptic number.

It is an amenable number.

161057781 is a deficient number, since it is larger than the sum of its proper divisors (85328139).

161057781 is a wasteful number, since it uses less digits than its factorization.

161057781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 922 (or 916 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 36.

The square root of 161057781 is about 12690.8542265680. The cubic root of 161057781 is about 544.0772546083.

The spelling of 161057781 in words is "one hundred sixty-one million, fifty-seven thousand, seven hundred eighty-one".