1645608989 has 2 divisors, whose sum is σ = 1645608990. Its totient is φ = 1645608988.

The previous prime is 1645608967. The next prime is 1645609001. The reversal of 1645608989 is 9898065461.

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., 1636202500 + 9406489 = 40450^2 + 3067^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645608989 - 2¹² = 1645604893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1645608919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822804494 + 822804495.

It is an arithmetic number, because the mean of its divisors is an integer number (822804495).

Almost surely, 2^1645608989 is an apocalyptic number.

It is an amenable number.

1645608989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645608989 is an equidigital number, since it uses as much as digits as its factorization.

1645608989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3732480, while the sum is 56.

The square root of 1645608989 is about 40566.1064067036. The cubic root of 1645608989 is about 1180.6165955407.

The spelling of 1645608989 in words is "one billion, six hundred forty-five million, six hundred eight thousand, nine hundred eighty-nine".