161858507 has 4 divisors (see below), whose sum is σ = 161886816. Its totient is φ = 161830200.

The previous prime is 161858503. The next prime is 161858509. The reversal of 161858507 is 705858161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 705858161 = 4229 ⋅166909.

It is a cyclic number.

It is not a de Polignac number, because 161858507 - 2² = 161858503 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161858503) 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, 2228 + ... + 18129.

It is an arithmetic number, because the mean of its divisors is an integer number (40471704).

Almost surely, 2^161858507 is an apocalyptic number.

161858507 is a deficient number, since it is larger than the sum of its proper divisors (28309).

161858507 is an equidigital number, since it uses as much as digits as its factorization.

161858507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28308.

The product of its (nonzero) digits is 67200, while the sum is 41.

The square root of 161858507 is about 12722.3624771502. The cubic root of 161858507 is about 544.9774218405.

The spelling of 161858507 in words is "one hundred sixty-one million, eight hundred fifty-eight thousand, five hundred seven".