261506431 has 4 divisors (see below), whose sum is σ = 261546264. Its totient is φ = 261466600.

The previous prime is 261506429. The next prime is 261506459. The reversal of 261506431 is 134605162.

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 261506431 - 2¹ = 261506429 is a prime.

It is a super-2 number, since 2×261506431² = 136771226908715522, which contains 22 as substring.

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 261506431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261506411) 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, 7480 + ... + 24061.

It is an arithmetic number, because the mean of its divisors is an integer number (65386566).

Almost surely, 2^261506431 is an apocalyptic number.

261506431 is a deficient number, since it is larger than the sum of its proper divisors (39833).

261506431 is an equidigital number, since it uses as much as digits as its factorization.

261506431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39832.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 261506431 is about 16171.1604716545. The cubic root of 261506431 is about 639.4807238089.

The spelling of 261506431 in words is "two hundred sixty-one million, five hundred six thousand, four hundred thirty-one".