1256880021 has 16 divisors (see below), whose sum is σ = 1684680000. Its totient is φ = 833511168.

The previous prime is 1256880017. The next prime is 1256880029. The reversal of 1256880021 is 1200886521.

It is not a de Polignac number, because 1256880021 - 2² = 1256880017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256880029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 837730 + ... + 839228.

It is an arithmetic number, because the mean of its divisors is an integer number (105292500).

Almost surely, 2^1256880021 is an apocalyptic number.

It is an amenable number.

1256880021 is a deficient number, since it is larger than the sum of its proper divisors (427799979).

1256880021 is a wasteful number, since it uses less digits than its factorization.

1256880021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2788.

The product of its (nonzero) digits is 7680, while the sum is 33.

The square root of 1256880021 is about 35452.5037338691. The cubic root of 1256880021 is about 1079.1900709132.

The spelling of 1256880021 in words is "one billion, two hundred fifty-six million, eight hundred eighty thousand, twenty-one".