255239991 has 40 divisors (see below), whose sum is σ = 397180080. Its totient is φ = 163150848.

The previous prime is 255239969. The next prime is 255240031. The reversal of 255239991 is 199932552.

255239991 is a `hidden beast` number, since 2 + 552 + 3 + 9 + 9 + 91 = 666.

It is not a de Polignac number, because 255239991 - 2¹³ = 255231799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255239911) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 453076 + ... + 453638.

It is an arithmetic number, because the mean of its divisors is an integer number (9929502).

Almost surely, 2^255239991 is an apocalyptic number.

255239991 is a deficient number, since it is larger than the sum of its proper divisors (141940089).

255239991 is a wasteful number, since it uses less digits than its factorization.

255239991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 797 (or 788 counting only the distinct ones).

The product of its digits is 218700, while the sum is 45.

The square root of 255239991 is about 15976.2320651648. The cubic root of 255239991 is about 634.3314442533.

The spelling of 255239991 in words is "two hundred fifty-five million, two hundred thirty-nine thousand, nine hundred ninety-one".