8157561901 has 12 divisors (see below), whose sum is σ = 8261624052. Its totient is φ = 8054537088.

The previous prime is 8157561799. The next prime is 8157561967. The reversal of 8157561901 is 1091657518.

It can be written as a sum of positive squares in 6 ways, for example, as 444155625 + 7713406276 = 21075^2 + 87826^2 .

It is not a de Polignac number, because 8157561901 - 2⁷ = 8157561773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8157561001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4263321 + ... + 4265233.

It is an arithmetic number, because the mean of its divisors is an integer number (688468671).

Almost surely, 2^8157561901 is an apocalyptic number.

It is an amenable number.

8157561901 is a deficient number, since it is larger than the sum of its proper divisors (104062151).

8157561901 is a wasteful number, since it uses less digits than its factorization.

8157561901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2400 (or 2243 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 43.

The square root of 8157561901 is about 90319.2222121072. Note that the first 4 decimals coincide. The cubic root of 8157561901 is about 2013.0448888674.

The spelling of 8157561901 in words is "eight billion, one hundred fifty-seven million, five hundred sixty-one thousand, nine hundred one".