1253991857 has 4 divisors (see below), whose sum is σ = 1256219760. Its totient is φ = 1251763956.

The previous prime is 1253991853. The next prime is 1253991889. The reversal of 1253991857 is 7581993521.

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, and also an emirpimes, since its reverse is a distinct semiprime: 7581993521 = 1297 ⋅5845793.

It is a cyclic number.

It is not a de Polignac number, because 1253991857 - 2² = 1253991853 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1253991853) 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, 1113107 + ... + 1114232.

It is an arithmetic number, because the mean of its divisors is an integer number (314054940).

Almost surely, 2^1253991857 is an apocalyptic number.

It is an amenable number.

1253991857 is a deficient number, since it is larger than the sum of its proper divisors (2227903).

1253991857 is an equidigital number, since it uses as much as digits as its factorization.

1253991857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2227902.

The product of its digits is 680400, while the sum is 50.

The square root of 1253991857 is about 35411.7474434685. The cubic root of 1253991857 is about 1078.3628192212.

The spelling of 1253991857 in words is "one billion, two hundred fifty-three million, nine hundred ninety-one thousand, eight hundred fifty-seven".