1255516621 has 4 divisors (see below), whose sum is σ = 1255990752. Its totient is φ = 1255042492.

The previous prime is 1255516607. The next prime is 1255516631. The reversal of 1255516621 is 1266155521.

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: 1266155521 = 10259 ⋅123419.

It is a cyclic number.

It is not a de Polignac number, because 1255516621 - 2⁹ = 1255516109 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 (1255516601) 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, 233071 + ... + 238396.

It is an arithmetic number, because the mean of its divisors is an integer number (313997688).

Almost surely, 2^1255516621 is an apocalyptic number.

It is an amenable number.

1255516621 is a deficient number, since it is larger than the sum of its proper divisors (474131).

1255516621 is an equidigital number, since it uses as much as digits as its factorization.

1255516621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 474130.

The product of its digits is 18000, while the sum is 34.

The square root of 1255516621 is about 35433.2699732892. The cubic root of 1255516621 is about 1078.7997127616.

The spelling of 1255516621 in words is "one billion, two hundred fifty-five million, five hundred sixteen thousand, six hundred twenty-one".