261451813 has 4 divisors (see below), whose sum is σ = 298802080. Its totient is φ = 224101548.

The previous prime is 261451807. The next prime is 261451847. The reversal of 261451813 is 318154162.

261451813 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a de Polignac number, because none of the positive numbers 2^k-261451813 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 (261451873) 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, 18675123 + ... + 18675136.

It is an arithmetic number, because the mean of its divisors is an integer number (74700520).

Almost surely, 2^261451813 is an apocalyptic number.

It is an amenable number.

261451813 is a deficient number, since it is larger than the sum of its proper divisors (37350267).

261451813 is an equidigital number, since it uses as much as digits as its factorization.

261451813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37350266.

The product of its digits is 5760, while the sum is 31.

The square root of 261451813 is about 16169.4716363894. The cubic root of 261451813 is about 639.4362002511.

The spelling of 261451813 in words is "two hundred sixty-one million, four hundred fifty-one thousand, eight hundred thirteen".