155656561 has 4 divisors (see below), whose sum is σ = 156516724. Its totient is φ = 154796400.

The previous prime is 155656547. The next prime is 155656583. The reversal of 155656561 is 165656551.

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 74926336 + 80730225 = 8656^2 + 8985^2 .

It is a cyclic number.

It is not a de Polignac number, because 155656561 - 2¹³ = 155648369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155656591) 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, 429810 + ... + 430171.

It is an arithmetic number, because the mean of its divisors is an integer number (39129181).

Almost surely, 2^155656561 is an apocalyptic number.

It is an amenable number.

155656561 is a deficient number, since it is larger than the sum of its proper divisors (860163).

155656561 is an equidigital number, since it uses as much as digits as its factorization.

155656561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 860162.

The product of its digits is 135000, while the sum is 40.

The square root of 155656561 is about 12476.2398582265. The cubic root of 155656561 is about 537.9259271163.

The spelling of 155656561 in words is "one hundred fifty-five million, six hundred fifty-six thousand, five hundred sixty-one".