261900518445 has 18 divisors (see below), whose sum is σ = 453966849258. Its totient is φ = 139678445568.

The previous prime is 261900518437. The next prime is 261900518557. The reversal of 261900518445 is 544815009162.

261900518445 is a `hidden beast` number, since 2 + 6 + 1 + 90 + 0 + 518 + 4 + 45 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 9481695876 + 252418822569 = 97374^2 + 502413^2 .

It is not a de Polignac number, because 261900518445 - 2³ = 261900518437 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 261900518445.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 3394861 + ... + 3471149.

Almost surely, 2^261900518445 is an apocalyptic number.

It is an amenable number.

261900518445 is a deficient number, since it is larger than the sum of its proper divisors (192066330813).

261900518445 is an frugal number, since it uses more digits than its factorization.

261900518445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152589 (or 76297 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

Multiplying 261900518445 by its sum of digits (45), we get a square (11785523330025 = 3433005²).

261900518445 divided by its sum of digits (45) gives a square (5820011521 = 76289²).

The spelling of 261900518445 in words is "two hundred sixty-one billion, nine hundred million, five hundred eighteen thousand, four hundred forty-five".