257020991 has 4 divisors (see below), whose sum is σ = 257312952. Its totient is φ = 256729032.

The previous prime is 257020987. The next prime is 257021027. The reversal of 257020991 is 199020752.

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 257020991 - 2² = 257020987 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 (257020091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 144656 + ... + 146421.

It is an arithmetic number, because the mean of its divisors is an integer number (64328238).

Almost surely, 2^257020991 is an apocalyptic number.

257020991 is a deficient number, since it is larger than the sum of its proper divisors (291961).

257020991 is an equidigital number, since it uses as much as digits as its factorization.

257020991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291960.

The product of its (nonzero) digits is 11340, while the sum is 35.

The square root of 257020991 is about 16031.8742198160. The cubic root of 257020991 is about 635.8034272122.

The spelling of 257020991 in words is "two hundred fifty-seven million, twenty thousand, nine hundred ninety-one".