261778701 has 4 divisors (see below), whose sum is σ = 349038272. Its totient is φ = 174519132.

The previous prime is 261778697. The next prime is 261778739. The reversal of 261778701 is 107877162.

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 not a de Polignac number, because 261778701 - 2² = 261778697 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 261778701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261778771) 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, 43629781 + ... + 43629786.

It is an arithmetic number, because the mean of its divisors is an integer number (87259568).

Almost surely, 2^261778701 is an apocalyptic number.

It is an amenable number.

261778701 is a deficient number, since it is larger than the sum of its proper divisors (87259571).

261778701 is an equidigital number, since it uses as much as digits as its factorization.

261778701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87259570.

The product of its (nonzero) digits is 32928, while the sum is 39.

The square root of 261778701 is about 16179.5766631887. The cubic root of 261778701 is about 639.7025807182.

It can be divided in two parts, 2617 and 78701, that added together give a palindrome (81318).

The spelling of 261778701 in words is "two hundred sixty-one million, seven hundred seventy-eight thousand, seven hundred one".