17640282721 has 2 divisors, whose sum is σ = 17640282722. Its totient is φ = 17640282720.

The previous prime is 17640282707. The next prime is 17640282731. The reversal of 17640282721 is 12728204671.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9927930321 + 7712352400 = 99639^2 + 87820^2 .

It is a cyclic number.

It is not a de Polignac number, because 17640282721 - 2²¹ = 17638185569 is a prime.

It is a super-2 number, since 2×17640282721² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (17640282701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8820141360 + 8820141361.

It is an arithmetic number, because the mean of its divisors is an integer number (8820141361).

Almost surely, 2^17640282721 is an apocalyptic number.

It is an amenable number.

17640282721 is a deficient number, since it is larger than the sum of its proper divisors (1).

17640282721 is an equidigital number, since it uses as much as digits as its factorization.

17640282721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 75264, while the sum is 40.

The spelling of 17640282721 in words is "seventeen billion, six hundred forty million, two hundred eighty-two thousand, seven hundred twenty-one".