249681561 has 16 divisors (see below), whose sum is σ = 345639360. Its totient is φ = 160130880.

The previous prime is 249681539. The next prime is 249681571. The reversal of 249681561 is 165186942.

It is not a de Polignac number, because 249681561 - 2⁵ = 249681529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (249681571) 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, 19551 + ... + 29691.

It is an arithmetic number, because the mean of its divisors is an integer number (21602460).

Almost surely, 2^249681561 is an apocalyptic number.

It is an amenable number.

249681561 is a deficient number, since it is larger than the sum of its proper divisors (95957799).

249681561 is a wasteful number, since it uses less digits than its factorization.

249681561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10456.

The product of its digits is 103680, while the sum is 42.

The square root of 249681561 is about 15801.3151667828. The cubic root of 249681561 is about 629.6929393028.

The spelling of 249681561 in words is "two hundred forty-nine million, six hundred eighty-one thousand, five hundred sixty-one".