1256406511 has 4 divisors (see below), whose sum is σ = 1256503024. Its totient is φ = 1256310000.

The previous prime is 1256406467. The next prime is 1256406553. The reversal of 1256406511 is 1156046521.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1256406511 - 2⁹ = 1256405999 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 (1256400511) 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, 24990 + ... + 56011.

It is an arithmetic number, because the mean of its divisors is an integer number (314125756).

Almost surely, 2^1256406511 is an apocalyptic number.

1256406511 is a deficient number, since it is larger than the sum of its proper divisors (96513).

1256406511 is an equidigital number, since it uses as much as digits as its factorization.

1256406511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96512.

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 1256406511 is about 35445.8250150846. The cubic root of 1256406511 is about 1079.0545311993.

The spelling of 1256406511 in words is "one billion, two hundred fifty-six million, four hundred six thousand, five hundred eleven".