1256265421 has 4 divisors (see below), whose sum is σ = 1296790144. Its totient is φ = 1215740700.

The previous prime is 1256265419. The next prime is 1256265449. The reversal of 1256265421 is 1245626521.

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.

It is a cyclic number.

It is not a de Polignac number, because 1256265421 - 2¹ = 1256265419 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 (1256265481) 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, 20262315 + ... + 20262376.

It is an arithmetic number, because the mean of its divisors is an integer number (324197536).

Almost surely, 2^1256265421 is an apocalyptic number.

It is an amenable number.

1256265421 is a deficient number, since it is larger than the sum of its proper divisors (40524723).

1256265421 is an equidigital number, since it uses as much as digits as its factorization.

1256265421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40524722.

The product of its digits is 28800, while the sum is 34.

The square root of 1256265421 is about 35443.8347389218. The cubic root of 1256265421 is about 1079.0141383536.

The spelling of 1256265421 in words is "one billion, two hundred fifty-six million, two hundred sixty-five thousand, four hundred twenty-one".