261636403253 has 4 divisors (see below), whose sum is σ = 261672814560. Its totient is φ = 261599991948.

The previous prime is 261636403229. The next prime is 261636403261. The reversal of 261636403253 is 352304636162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261636403253 - 2¹⁶ = 261636337717 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261636403253.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261636400253) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18194873 + ... + 18209246.

It is an arithmetic number, because the mean of its divisors is an integer number (65418203640).

Almost surely, 2^261636403253 is an apocalyptic number.

It is an amenable number.

261636403253 is a deficient number, since it is larger than the sum of its proper divisors (36411307).

261636403253 is an equidigital number, since it uses as much as digits as its factorization.

261636403253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36411306.

The product of its (nonzero) digits is 466560, while the sum is 41.

The spelling of 261636403253 in words is "two hundred sixty-one billion, six hundred thirty-six million, four hundred three thousand, two hundred fifty-three".