261499961 has 4 divisors (see below), whose sum is σ = 261612624. Its totient is φ = 261387300.

The previous prime is 261499951. The next prime is 261499993. The reversal of 261499961 is 169994162.

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 not a de Polignac number, because 261499961 - 2⁶ = 261499897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261499951) 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, 52775 + ... + 57516.

It is an arithmetic number, because the mean of its divisors is an integer number (65403156).

Almost surely, 2^261499961 is an apocalyptic number.

It is an amenable number.

261499961 is a deficient number, since it is larger than the sum of its proper divisors (112663).

261499961 is a wasteful number, since it uses less digits than its factorization.

261499961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112662.

The product of its digits is 209952, while the sum is 47.

The square root of 261499961 is about 16170.9604229310. The cubic root of 261499961 is about 639.4754499113.

The spelling of 261499961 in words is "two hundred sixty-one million, four hundred ninety-nine thousand, nine hundred sixty-one".