1581273481 has 2 divisors, whose sum is σ = 1581273482. Its totient is φ = 1581273480.

The previous prime is 1581273467. The next prime is 1581273503. The reversal of 1581273481 is 1843721851.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1572915600 + 8357881 = 39660^2 + 2891^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1581273481 is a prime.

It is a super-2 number, since 2×1581273481² = 5000851643427714722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1581273431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790636740 + 790636741.

It is an arithmetic number, because the mean of its divisors is an integer number (790636741).

Almost surely, 2^1581273481 is an apocalyptic number.

It is an amenable number.

1581273481 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581273481 is an equidigital number, since it uses as much as digits as its factorization.

1581273481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 53760, while the sum is 40.

The square root of 1581273481 is about 39765.2295479355. The cubic root of 1581273481 is about 1165.0261203597.

The spelling of 1581273481 in words is "one billion, five hundred eighty-one million, two hundred seventy-three thousand, four hundred eighty-one".