1255721531 has 4 divisors (see below), whose sum is σ = 1256070432. Its totient is φ = 1255372632.

The previous prime is 1255721479. The next prime is 1255721543. The reversal of 1255721531 is 1351275521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1351275521 = 47 ⋅28750543.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1255721531 is a prime.

It is a super-2 number, since 2×1255721531² = 3153673126833967922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1255721581) 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, 168995 + ... + 176268.

It is an arithmetic number, because the mean of its divisors is an integer number (314017608).

Almost surely, 2^1255721531 is an apocalyptic number.

1255721531 is a deficient number, since it is larger than the sum of its proper divisors (348901).

1255721531 is an equidigital number, since it uses as much as digits as its factorization.

1255721531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348900.

The product of its digits is 10500, while the sum is 32.

The square root of 1255721531 is about 35436.1613468502. The cubic root of 1255721531 is about 1078.8583990481.

The spelling of 1255721531 in words is "one billion, two hundred fifty-five million, seven hundred twenty-one thousand, five hundred thirty-one".