121491561 has 16 divisors (see below), whose sum is σ = 165784320. Its totient is φ = 79114320.

The previous prime is 121491553. The next prime is 121491593. The reversal of 121491561 is 165194121.

It is not a de Polignac number, because 121491561 - 2³ = 121491553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121491521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26746 + ... + 30956.

It is an arithmetic number, because the mean of its divisors is an integer number (10361520).

Almost surely, 2^121491561 is an apocalyptic number.

It is an amenable number.

121491561 is a deficient number, since it is larger than the sum of its proper divisors (44292759).

121491561 is a wasteful number, since it uses less digits than its factorization.

121491561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4436.

The product of its digits is 2160, while the sum is 30.

The square root of 121491561 is about 11022.3210350634. The cubic root of 121491561 is about 495.2776200053.

The spelling of 121491561 in words is "one hundred twenty-one million, four hundred ninety-one thousand, five hundred sixty-one".