161898643 has 4 divisors (see below), whose sum is σ = 166274320. Its totient is φ = 157522968.

The previous prime is 161898641. The next prime is 161898683. The reversal of 161898643 is 346898161.

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 161898643 - 2¹ = 161898641 is a prime.

It is a super-2 number, since 2×161898643² = 52422341210482898, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161898593 and 161898602.

It is not an unprimeable number, because it can be changed into a prime (161898641) 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, 2187783 + ... + 2187856.

It is an arithmetic number, because the mean of its divisors is an integer number (41568580).

Almost surely, 2^161898643 is an apocalyptic number.

161898643 is a deficient number, since it is larger than the sum of its proper divisors (4375677).

161898643 is an equidigital number, since it uses as much as digits as its factorization.

161898643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4375676.

The product of its digits is 248832, while the sum is 46.

The square root of 161898643 is about 12723.9397593670. The cubic root of 161898643 is about 545.0224640742.

The spelling of 161898643 in words is "one hundred sixty-one million, eight hundred ninety-eight thousand, six hundred forty-three".