161890305 has 16 divisors (see below), whose sum is σ = 259315584. Its totient is φ = 86244480.

The previous prime is 161890283. The next prime is 161890321. The reversal of 161890305 is 503098161.

It is not a de Polignac number, because 161890305 - 2⁵ = 161890273 is a prime.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8925 + ... + 20085.

It is an arithmetic number, because the mean of its divisors is an integer number (16207224).

It is a Proth number, since it is equal to 9881 ⋅ 2¹⁴ + 1 and 9881 < 2¹⁴.

Almost surely, 2^161890305 is an apocalyptic number.

161890305 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

161890305 is a deficient number, since it is larger than the sum of its proper divisors (97425279).

161890305 is a wasteful number, since it uses less digits than its factorization.

161890305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12136.

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 161890305 is about 12723.6121050588. The cubic root of 161890305 is about 545.0131074479.

The spelling of 161890305 in words is "one hundred sixty-one million, eight hundred ninety thousand, three hundred five".