40643619581 has 2 divisors, whose sum is σ = 40643619582. Its totient is φ = 40643619580.

The previous prime is 40643619571. The next prime is 40643619589. The reversal of 40643619581 is 18591634604.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25473756025 + 15169863556 = 159605^2 + 123166^2 .

It is a cyclic number.

It is not a de Polignac number, because 40643619581 - 2³⁴ = 23463750397 is a prime.

It is a super-2 number, since 2×40643619581² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40643619589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20321809790 + 20321809791.

It is an arithmetic number, because the mean of its divisors is an integer number (20321809791).

Almost surely, 2^40643619581 is an apocalyptic number.

It is an amenable number.

40643619581 is a deficient number, since it is larger than the sum of its proper divisors (1).

40643619581 is an equidigital number, since it uses as much as digits as its factorization.

40643619581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 622080, while the sum is 47.

The spelling of 40643619581 in words is "forty billion, six hundred forty-three million, six hundred nineteen thousand, five hundred eighty-one".