2131561645 has 24 divisors (see below), whose sum is σ = 2731569120. Its totient is φ = 1592388000.

The previous prime is 2131561633. The next prime is 2131561661. The reversal of 2131561645 is 5461651312.

It is not a de Polignac number, because 2131561645 - 2¹⁹ = 2131037357 is a prime.

It is a super-3 number, since 3×2131561645³ (a number of 29 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 2131561645.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 476670 + ... + 481120.

It is an arithmetic number, because the mean of its divisors is an integer number (113815380).

Almost surely, 2^2131561645 is an apocalyptic number.

It is an amenable number.

2131561645 is a deficient number, since it is larger than the sum of its proper divisors (600007475).

2131561645 is an equidigital number, since it uses as much as digits as its factorization.

2131561645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4617 (or 4546 counting only the distinct ones).

The product of its digits is 21600, while the sum is 34.

The square root of 2131561645 is about 46168.8384627554. The cubic root of 2131561645 is about 1286.9627169697.

The spelling of 2131561645 in words is "two billion, one hundred thirty-one million, five hundred sixty-one thousand, six hundred forty-five".