261731601 has 8 divisors (see below), whose sum is σ = 387750560. Its totient is φ = 174487716.

The previous prime is 261731567. The next prime is 261731621. The reversal of 261731601 is 106137162.

261731601 is a `hidden beast` number, since 26 + 1 + 7 + 31 + 601 = 666.

It is not a de Polignac number, because 261731601 - 2⁶ = 261731537 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 9693763 = 261731601 / (2 + 6 + 1 + 7 + 3 + 1 + 6 + 0 + 1).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261731621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4846855 + ... + 4846908.

It is an arithmetic number, because the mean of its divisors is an integer number (48468820).

Almost surely, 2^261731601 is an apocalyptic number.

It is an amenable number.

261731601 is a deficient number, since it is larger than the sum of its proper divisors (126018959).

261731601 is an equidigital number, since it uses as much as digits as its factorization.

261731601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9693772 (or 9693766 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 261731601 is about 16178.1210590105. The cubic root of 261731601 is about 639.6642126887.

Adding to 261731601 its reverse (106137162), we get a palindrome (367868763).

The spelling of 261731601 in words is "two hundred sixty-one million, seven hundred thirty-one thousand, six hundred one".