155720561 has 16 divisors (see below), whose sum is σ = 175190400. Its totient is φ = 137541888.

The previous prime is 155720503. The next prime is 155720563. The reversal of 155720561 is 165027551.

It is a cyclic number.

It is not a de Polignac number, because 155720561 - 2⁶ = 155720497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155720563) 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, 32996 + ... + 37418.

It is an arithmetic number, because the mean of its divisors is an integer number (10949400).

Almost surely, 2^155720561 is an apocalyptic number.

It is an amenable number.

155720561 is a deficient number, since it is larger than the sum of its proper divisors (19469839).

155720561 is a wasteful number, since it uses less digits than its factorization.

155720561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4568.

The product of its (nonzero) digits is 10500, while the sum is 32.

The square root of 155720561 is about 12478.8044699803. The cubic root of 155720561 is about 537.9996418418. Note that the first 3 decimals are identical.

The spelling of 155720561 in words is "one hundred fifty-five million, seven hundred twenty thousand, five hundred sixty-one".