101561491 has 4 divisors (see below), whose sum is σ = 105977232. Its totient is φ = 97145752.

The previous prime is 101561477. The next prime is 101561507. The reversal of 101561491 is 194165101.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-101561491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (101561431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2207836 + ... + 2207881.

It is an arithmetic number, because the mean of its divisors is an integer number (26494308).

Almost surely, 2^101561491 is an apocalyptic number.

101561491 is a deficient number, since it is larger than the sum of its proper divisors (4415741).

101561491 is an equidigital number, since it uses as much as digits as its factorization.

101561491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4415740.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 101561491 is about 10077.7721248300. The cubic root of 101561491 is about 466.5623495288.

The spelling of 101561491 in words is "one hundred one million, five hundred sixty-one thousand, four hundred ninety-one".