1581023881 has 2 divisors, whose sum is σ = 1581023882. Its totient is φ = 1581023880.

The previous prime is 1581023863. The next prime is 1581023897. The reversal of 1581023881 is 1883201851.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1504198656 + 76825225 = 38784^2 + 8765^2 .

It is an emirp because it is prime and its reverse (1883201851) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1581023881 - 2⁵ = 1581023849 is a prime.

It is a super-2 number, since 2×1581023881² = 4999273024584604322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1581023881.

It is not a weakly prime, because it can be changed into another prime (1581023861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790511940 + 790511941.

It is an arithmetic number, because the mean of its divisors is an integer number (790511941).

Almost surely, 2^1581023881 is an apocalyptic number.

It is an amenable number.

1581023881 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581023881 is an equidigital number, since it uses as much as digits as its factorization.

1581023881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15360, while the sum is 37.

The square root of 1581023881 is about 39762.0910038695. The cubic root of 1581023881 is about 1164.9648183301.

The spelling of 1581023881 in words is "one billion, five hundred eighty-one million, twenty-three thousand, eight hundred eighty-one".