17916245621 has 2 divisors, whose sum is σ = 17916245622. Its totient is φ = 17916245620.

The previous prime is 17916245597. The next prime is 17916245657. The reversal of 17916245621 is 12654261971.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17666131396 + 250114225 = 132914^2 + 15815^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-17916245621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17916245021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8958122810 + 8958122811.

It is an arithmetic number, because the mean of its divisors is an integer number (8958122811).

Almost surely, 2^17916245621 is an apocalyptic number.

It is an amenable number.

17916245621 is a deficient number, since it is larger than the sum of its proper divisors (1).

17916245621 is an equidigital number, since it uses as much as digits as its factorization.

17916245621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 44.

The spelling of 17916245621 in words is "seventeen billion, nine hundred sixteen million, two hundred forty-five thousand, six hundred twenty-one".