261731407 has 4 divisors (see below), whose sum is σ = 299121616. Its totient is φ = 224341200.

The previous prime is 261731399. The next prime is 261731417. The reversal of 261731407 is 704137162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261731407 - 2³ = 261731399 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 (261731417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18695094 + ... + 18695107.

It is an arithmetic number, because the mean of its divisors is an integer number (74780404).

Almost surely, 2^261731407 is an apocalyptic number.

261731407 is a deficient number, since it is larger than the sum of its proper divisors (37390209).

261731407 is an equidigital number, since it uses as much as digits as its factorization.

261731407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37390208.

The product of its (nonzero) digits is 7056, while the sum is 31.

The square root of 261731407 is about 16178.1150632575. The cubic root of 261731407 is about 639.6640546453.

Adding to 261731407 its reverse (704137162), we get a palindrome (965868569).

The spelling of 261731407 in words is "two hundred sixty-one million, seven hundred thirty-one thousand, four hundred seven".