7138661581 has 2 divisors, whose sum is σ = 7138661582. Its totient is φ = 7138661580.

The previous prime is 7138661561. The next prime is 7138661587. The reversal of 7138661581 is 1851668317.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7063562025 + 75099556 = 84045^2 + 8666^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7138661581 is a prime.

It is a super-2 number, since 2×7138661581² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7138661587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3569330790 + 3569330791.

It is an arithmetic number, because the mean of its divisors is an integer number (3569330791).

Almost surely, 2^7138661581 is an apocalyptic number.

It is an amenable number.

7138661581 is a deficient number, since it is larger than the sum of its proper divisors (1).

7138661581 is an equidigital number, since it uses as much as digits as its factorization.

7138661581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 46.

The square root of 7138661581 is about 84490.6005482267. The cubic root of 7138661581 is about 1925.4796426433.

The spelling of 7138661581 in words is "seven billion, one hundred thirty-eight million, six hundred sixty-one thousand, five hundred eighty-one".