640615181 has 2 divisors, whose sum is σ = 640615182. Its totient is φ = 640615180.

The previous prime is 640615061. The next prime is 640615211. The reversal of 640615181 is 181516046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 379275625 + 261339556 = 19475^2 + 16166^2 .

It is a cyclic number.

It is not a de Polignac number, because 640615181 - 2¹⁰ = 640614157 is a prime.

It is a super-2 number, since 2×640615181² = 820775620255325522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640614181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320307590 + 320307591.

It is an arithmetic number, because the mean of its divisors is an integer number (320307591).

Almost surely, 2^640615181 is an apocalyptic number.

It is an amenable number.

640615181 is a deficient number, since it is larger than the sum of its proper divisors (1).

640615181 is an equidigital number, since it uses as much as digits as its factorization.

640615181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 640615181 is about 25310.3769430643. The cubic root of 640615181 is about 862.0499057746.

The spelling of 640615181 in words is "six hundred forty million, six hundred fifteen thousand, one hundred eighty-one".