1256054021 has 4 divisors (see below), whose sum is σ = 1257082272. Its totient is φ = 1255025772.

The previous prime is 1256053999. The next prime is 1256054083. The reversal of 1256054021 is 1204506521.

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: 1204506521 = 97 ⋅12417593.

It is a cyclic number.

It is not a de Polignac number, because 1256054021 - 2¹⁰ = 1256052997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256054321) 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, 512291 + ... + 514736.

It is an arithmetic number, because the mean of its divisors is an integer number (314270568).

Almost surely, 2^1256054021 is an apocalyptic number.

It is an amenable number.

1256054021 is a deficient number, since it is larger than the sum of its proper divisors (1028251).

1256054021 is a wasteful number, since it uses less digits than its factorization.

1256054021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1028250.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 1256054021 is about 35440.8524304933. The cubic root of 1256054021 is about 1078.9536107026.

The spelling of 1256054021 in words is "one billion, two hundred fifty-six million, fifty-four thousand, twenty-one".