256038991 has 4 divisors (see below), whose sum is σ = 275734312. Its totient is φ = 236343672.

The previous prime is 256038983. The next prime is 256038997. The reversal of 256038991 is 199830652.

It is a happy number.

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 256038991 - 2³ = 256038983 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 (256038997) 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, 9847641 + ... + 9847666.

It is an arithmetic number, because the mean of its divisors is an integer number (68933578).

Almost surely, 2^256038991 is an apocalyptic number.

256038991 is a deficient number, since it is larger than the sum of its proper divisors (19695321).

256038991 is a wasteful number, since it uses less digits than its factorization.

256038991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19695320.

The product of its (nonzero) digits is 116640, while the sum is 43.

The square root of 256038991 is about 16001.2184223577. The cubic root of 256038991 is about 634.9926557937.

The spelling of 256038991 in words is "two hundred fifty-six million, thirty-eight thousand, nine hundred ninety-one".