1581636 has 48 divisors (see below), whose sum is σ = 4444160. Its totient is φ = 427680.

The previous prime is 1581623. The next prime is 1581637. The reversal of 1581636 is 6361851.

It is not an unprimeable number, because it can be changed into a prime (1581637) 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, 1101 + ... + 2091.

2^1581636 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1581636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2222080).

1581636 is an abundant number, since it is smaller than the sum of its proper divisors (2862524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1581636 is a wasteful number, since it uses less digits than its factorization.

1581636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1024 (or 1022 counting only the distinct ones).

The product of its digits is 4320, while the sum is 30.

The square root of 1581636 is about 1257.6311064855. The cubic root of 1581636 is about 116.5115143930.

The spelling of 1581636 in words is "one million, five hundred eighty-one thousand, six hundred thirty-six".