1255805751721 has 4 divisors (see below), whose sum is σ = 1261437167872. Its totient is φ = 1250174335572.

The previous prime is 1255805751709. The next prime is 1255805751727. The reversal of 1255805751721 is 1271575085521.

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 1255805751721 - 2¹³ = 1255805743529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1255805751727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2815707741 + ... + 2815708186.

It is an arithmetic number, because the mean of its divisors is an integer number (315359291968).

Almost surely, 2^{1255805751721} is an apocalyptic number.

It is an amenable number.

1255805751721 is a deficient number, since it is larger than the sum of its proper divisors (5631416151).

1255805751721 is an equidigital number, since it uses as much as digits as its factorization.

1255805751721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5631416150.

The product of its (nonzero) digits is 980000, while the sum is 49.

The spelling of 1255805751721 in words is "one trillion, two hundred fifty-five billion, eight hundred five million, seven hundred fifty-one thousand, seven hundred twenty-one".