1256745251 has 4 divisors (see below), whose sum is σ = 1265918712. Its totient is φ = 1247571792.

The previous prime is 1256745229. The next prime is 1256745337. The reversal of 1256745251 is 1525476521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1525476521 = 17 ⋅89733913.

It is a cyclic number.

It is not a de Polignac number, because 1256745251 - 2⁶ = 1256745187 is a prime.

It is a super-2 number, since 2×1256745251² = 3158817251822106002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1256745211) 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, 4586525 + ... + 4586798.

It is an arithmetic number, because the mean of its divisors is an integer number (316479678).

Almost surely, 2^1256745251 is an apocalyptic number.

1256745251 is a deficient number, since it is larger than the sum of its proper divisors (9173461).

1256745251 is an equidigital number, since it uses as much as digits as its factorization.

1256745251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9173460.

The product of its digits is 84000, while the sum is 38.

The square root of 1256745251 is about 35450.6029708946. The cubic root of 1256745251 is about 1079.1514971851.

The spelling of 1256745251 in words is "one billion, two hundred fifty-six million, seven hundred forty-five thousand, two hundred fifty-one".