124991561 has 4 divisors (see below), whose sum is σ = 125016852. Its totient is φ = 124966272.

The previous prime is 124991551. The next prime is 124991563. The reversal of 124991561 is 165199421.

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

It can be written as a sum of positive squares in 2 ways, for example, as 31753225 + 93238336 = 5635^2 + 9656^2 .

It is a cyclic number.

It is not a de Polignac number, because 124991561 - 2¹⁸ = 124729417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (124991563) 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, 2540 + ... + 16013.

It is an arithmetic number, because the mean of its divisors is an integer number (31254213).

Almost surely, 2^124991561 is an apocalyptic number.

It is an amenable number.

124991561 is a deficient number, since it is larger than the sum of its proper divisors (25291).

124991561 is an equidigital number, since it uses as much as digits as its factorization.

124991561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25290.

The product of its digits is 19440, while the sum is 38.

The square root of 124991561 is about 11179.9624775757. The cubic root of 124991561 is about 499.9887477468.

The spelling of 124991561 in words is "one hundred twenty-four million, nine hundred ninety-one thousand, five hundred sixty-one".