1581138 has 48 divisors (see below), whose sum is σ = 3832920. Its totient is φ = 467712.

The previous prime is 1581131. The next prime is 1581157. The reversal of 1581138 is 8311851.

It can be written as a sum of positive squares in 4 ways, for example, as 870489 + 710649 = 933^2 + 843^2 .

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581131) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6670 + ... + 6902.

2^1581138 is an apocalyptic number.

1581138 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1581138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1916460).

1581138 is an abundant number, since it is smaller than the sum of its proper divisors (2251782).

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

1581138 is a wasteful number, since it uses less digits than its factorization.

1581138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283 (or 280 counting only the distinct ones).

The product of its digits is 960, while the sum is 27.

The square root of 1581138 is about 1257.4330996121. The cubic root of 1581138 is about 116.4992846880.

Adding to 1581138 its reverse (8311851), we get a palindrome (9892989).

It can be divided in two parts, 158 and 1138, that added together give a 4-th power (1296 = 6⁴).

The spelling of 1581138 in words is "one million, five hundred eighty-one thousand, one hundred thirty-eight".