17621720881 has 2 divisors, whose sum is σ = 17621720882. Its totient is φ = 17621720880.

The previous prime is 17621720813. The next prime is 17621720887. The reversal of 17621720881 is 18802712671.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17560490256 + 61230625 = 132516^2 + 7825^2 .

It is a cyclic number.

It is not a de Polignac number, because 17621720881 - 2²⁷ = 17487503153 is a prime.

It is a super-2 number, since 2×17621720881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (17621720887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8810860440 + 8810860441.

It is an arithmetic number, because the mean of its divisors is an integer number (8810860441).

Almost surely, 2^17621720881 is an apocalyptic number.

It is an amenable number.

17621720881 is a deficient number, since it is larger than the sum of its proper divisors (1).

17621720881 is an equidigital number, since it uses as much as digits as its factorization.

17621720881 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 43.

The spelling of 17621720881 in words is "seventeen billion, six hundred twenty-one million, seven hundred twenty thousand, eight hundred eighty-one".