261399863 has 2 divisors, whose sum is σ = 261399864. Its totient is φ = 261399862.

The previous prime is 261399847. The next prime is 261399877. The reversal of 261399863 is 368993162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261399863 - 2⁴ = 261399847 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261399883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130699931 + 130699932.

It is an arithmetic number, because the mean of its divisors is an integer number (130699932).

Almost surely, 2^261399863 is an apocalyptic number.

261399863 is a deficient number, since it is larger than the sum of its proper divisors (1).

261399863 is an equidigital number, since it uses as much as digits as its factorization.

261399863 is an evil number, because the sum of its binary digits is even.

The product of its digits is 419904, while the sum is 47.

The square root of 261399863 is about 16167.8651342717. The cubic root of 261399863 is about 639.3938458421.

It can be divided in two parts, 261399 and 863, that added together give a palindrome (262262).

The spelling of 261399863 in words is "two hundred sixty-one million, three hundred ninety-nine thousand, eight hundred sixty-three".