1681581213 has 12 divisors (see below), whose sum is σ = 2615793180. Its totient is φ = 1034819136.

The previous prime is 1681581203. The next prime is 1681581227. The reversal of 1681581213 is 3121851861.

1681581213 is a `hidden beast` number, since 1 + 68 + 1 + 581 + 2 + 13 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 404733924 + 1276847289 = 20118^2 + 35733^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1681581213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681581203) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7186128 + ... + 7186361.

It is an arithmetic number, because the mean of its divisors is an integer number (217982765).

Almost surely, 2^1681581213 is an apocalyptic number.

1681581213 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

1681581213 is a deficient number, since it is larger than the sum of its proper divisors (934211967).

1681581213 is a wasteful number, since it uses less digits than its factorization.

1681581213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14372508 (or 14372505 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 1681581213 is about 41007.0873508470. The cubic root of 1681581213 is about 1189.1572341857.

The spelling of 1681581213 in words is "one billion, six hundred eighty-one million, five hundred eighty-one thousand, two hundred thirteen".