1581005381 has 16 divisors (see below), whose sum is σ = 1649239680. Its totient is φ = 1514358720.

The previous prime is 1581005369. The next prime is 1581005407. The reversal of 1581005381 is 1835001851.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1581005381 - 2²² = 1576811077 is a prime.

It is a super-2 number, since 2×1581005381² = 4999156029501910322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581005341) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1150811 + ... + 1152183.

It is an arithmetic number, because the mean of its divisors is an integer number (103077480).

Almost surely, 2^1581005381 is an apocalyptic number.

It is an amenable number.

1581005381 is a deficient number, since it is larger than the sum of its proper divisors (68234299).

1581005381 is a wasteful number, since it uses less digits than its factorization.

1581005381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1916.

The product of its (nonzero) digits is 4800, while the sum is 32.

The square root of 1581005381 is about 39761.8583695481. The cubic root of 1581005381 is about 1164.9602744533.

The spelling of 1581005381 in words is "one billion, five hundred eighty-one million, five thousand, three hundred eighty-one".