16620621989 has 2 divisors, whose sum is σ = 16620621990. Its totient is φ = 16620621988.

The previous prime is 16620621917. The next prime is 16620622003. The reversal of 16620621989 is 98912602661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16519960900 + 100661089 = 128530^2 + 10033^2 .

It is an emirp because it is prime and its reverse (98912602661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16620621989 - 2¹⁶ = 16620556453 is a prime.

It is a super-2 number, since 2×16620621989² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16620626989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8310310994 + 8310310995.

It is an arithmetic number, because the mean of its divisors is an integer number (8310310995).

Almost surely, 2^16620621989 is an apocalyptic number.

It is an amenable number.

16620621989 is a deficient number, since it is larger than the sum of its proper divisors (1).

16620621989 is an equidigital number, since it uses as much as digits as its factorization.

16620621989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 559872, while the sum is 50.

The spelling of 16620621989 in words is "sixteen billion, six hundred twenty million, six hundred twenty-one thousand, nine hundred eighty-nine".