123540157561 has 8 divisors (see below), whose sum is σ = 124264574280. Its totient is φ = 122815859712.

The previous prime is 123540157553. The next prime is 123540157571. The reversal of 123540157561 is 165751045321.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 14256360000 + 109283797561 = 119400^2 + 330581^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 123540157561 - 2³ = 123540157553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (123540157571) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2890201 + ... + 2932633.

It is an arithmetic number, because the mean of its divisors is an integer number (15533071785).

Almost surely, 2^123540157561 is an apocalyptic number.

It is an amenable number.

123540157561 is a deficient number, since it is larger than the sum of its proper divisors (724416719).

123540157561 is a wasteful number, since it uses less digits than its factorization.

123540157561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59435.

The product of its (nonzero) digits is 126000, while the sum is 40.

The spelling of 123540157561 in words is "one hundred twenty-three billion, five hundred forty million, one hundred fifty-seven thousand, five hundred sixty-one".