1659959621 has 2 divisors, whose sum is σ = 1659959622. Its totient is φ = 1659959620.

The previous prime is 1659959603. The next prime is 1659959641. The reversal of 1659959621 is 1269599561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1109822596 + 550137025 = 33314^2 + 23455^2 .

It is an emirp because it is prime and its reverse (1269599561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1659959621 - 2¹⁴ = 1659943237 is a prime.

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 (1659959641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 829979810 + 829979811.

It is an arithmetic number, because the mean of its divisors is an integer number (829979811).

Almost surely, 2^1659959621 is an apocalyptic number.

It is an amenable number.

1659959621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1659959621 is an equidigital number, since it uses as much as digits as its factorization.

1659959621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1312200, while the sum is 53.

The square root of 1659959621 is about 40742.6020401250. The cubic root of 1659959621 is about 1184.0385469269.

It can be divided in two parts, 165995 and 9621, that added together give a cube (175616 = 56³).

The spelling of 1659959621 in words is "one billion, six hundred fifty-nine million, nine hundred fifty-nine thousand, six hundred twenty-one".