3951813581 has 2 divisors, whose sum is σ = 3951813582. Its totient is φ = 3951813580.

The previous prime is 3951813539. The next prime is 3951813641. The reversal of 3951813581 is 1853181593.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2336175556 + 1615638025 = 48334^2 + 40195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3951813581 is a prime.

It is a super-2 number, since 2×3951813581² = 31233661157952087122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3951813521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1975906790 + 1975906791.

It is an arithmetic number, because the mean of its divisors is an integer number (1975906791).

Almost surely, 2^3951813581 is an apocalyptic number.

It is an amenable number.

3951813581 is a deficient number, since it is larger than the sum of its proper divisors (1).

3951813581 is an equidigital number, since it uses as much as digits as its factorization.

3951813581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129600, while the sum is 44.

The square root of 3951813581 is about 62863.4518699061. The cubic root of 3951813581 is about 1581.0010188449.

The spelling of 3951813581 in words is "three billion, nine hundred fifty-one million, eight hundred thirteen thousand, five hundred eighty-one".