161558503 has 4 divisors (see below), whose sum is σ = 162234720. Its totient is φ = 160882288.

The previous prime is 161558471. The next prime is 161558519. The reversal of 161558503 is 305855161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161558503 - 2⁵ = 161558471 is a prime.

It is a super-2 number, since 2×161558503² = 52202299783202018, 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 (161558203) 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, 337750 + ... + 338227.

It is an arithmetic number, because the mean of its divisors is an integer number (40558680).

Almost surely, 2^161558503 is an apocalyptic number.

161558503 is a deficient number, since it is larger than the sum of its proper divisors (676217).

161558503 is an equidigital number, since it uses as much as digits as its factorization.

161558503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 676216.

The product of its (nonzero) digits is 18000, while the sum is 34.

The square root of 161558503 is about 12710.5665884728. The cubic root of 161558503 is about 544.6405092158.

The spelling of 161558503 in words is "one hundred sixty-one million, five hundred fifty-eight thousand, five hundred three".