161391553 has 4 divisors (see below), whose sum is σ = 161831680. Its totient is φ = 160951428.

The previous prime is 161391551. The next prime is 161391563. The reversal of 161391553 is 355193161.

It is a happy number.

161391553 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161391553 - 2¹ = 161391551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161391551) 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, 219513 + ... + 220246.

It is an arithmetic number, because the mean of its divisors is an integer number (40457920).

Almost surely, 2^161391553 is an apocalyptic number.

It is an amenable number.

161391553 is a deficient number, since it is larger than the sum of its proper divisors (440127).

161391553 is an equidigital number, since it uses as much as digits as its factorization.

161391553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440126.

The product of its digits is 12150, while the sum is 34.

The square root of 161391553 is about 12703.9975204658. The cubic root of 161391553 is about 544.4528391767.

The spelling of 161391553 in words is "one hundred sixty-one million, three hundred ninety-one thousand, five hundred fifty-three".