161051391 has 24 divisors (see below), whose sum is σ = 246205440. Its totient is φ = 101163600.

The previous prime is 161051381. The next prime is 161051393. The reversal of 161051391 is 193150161.

161051391 is a `hidden beast` number, since 1 + 61 + 0 + 513 + 91 = 666.

It is not a de Polignac number, because 161051391 - 2⁶ = 161051327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161051393) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30196 + ... + 35126.

It is an arithmetic number, because the mean of its divisors is an integer number (10258560).

Almost surely, 2^161051391 is an apocalyptic number.

161051391 is a deficient number, since it is larger than the sum of its proper divisors (85154049).

161051391 is a wasteful number, since it uses less digits than its factorization.

161051391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5147 (or 5144 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 161051391 is about 12690.6024679682. The cubic root of 161051391 is about 544.0700590548.

The spelling of 161051391 in words is "one hundred sixty-one million, fifty-one thousand, three hundred ninety-one".