651623581681 has 2 divisors, whose sum is σ = 651623581682. Its totient is φ = 651623581680.

The previous prime is 651623581621. The next prime is 651623581711. The reversal of 651623581681 is 186185326156.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 332352250000 + 319271331681 = 576500^2 + 565041^2 .

It is a cyclic number.

It is not a de Polignac number, because 651623581681 - 2¹⁵ = 651623548913 is a prime.

It is a super-2 number, since 2×651623581681² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (651623581621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 325811790840 + 325811790841.

It is an arithmetic number, because the mean of its divisors is an integer number (325811790841).

Almost surely, 2^651623581681 is an apocalyptic number.

It is an amenable number.

651623581681 is a deficient number, since it is larger than the sum of its proper divisors (1).

651623581681 is an equidigital number, since it uses as much as digits as its factorization.

651623581681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2073600, while the sum is 52.

The spelling of 651623581681 in words is "six hundred fifty-one billion, six hundred twenty-three million, five hundred eighty-one thousand, six hundred eighty-one".