1581447981 has 32 divisors (see below), whose sum is σ = 2259025920. Its totient is φ = 981892800.

The previous prime is 1581447979. The next prime is 1581448003. The reversal of 1581447981 is 1897441851.

It is not a de Polignac number, because 1581447981 - 2¹ = 1581447979 is a prime.

It is a super-2 number, since 2×1581447981² = 5001955433217952722, 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 1581447981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581447911) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1032186 + ... + 1033716.

It is an arithmetic number, because the mean of its divisors is an integer number (70594560).

Almost surely, 2^1581447981 is an apocalyptic number.

It is an amenable number.

1581447981 is a deficient number, since it is larger than the sum of its proper divisors (677577939).

1581447981 is a wasteful number, since it uses less digits than its factorization.

1581447981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1977.

The product of its digits is 322560, while the sum is 48.

The square root of 1581447981 is about 39767.4236153161. The cubic root of 1581447981 is about 1165.0689739168.

The spelling of 1581447981 in words is "one billion, five hundred eighty-one million, four hundred forty-seven thousand, nine hundred eighty-one".