1618721659 has 2 divisors, whose sum is σ = 1618721660. Its totient is φ = 1618721658.

The previous prime is 1618721639. The next prime is 1618721683. The reversal of 1618721659 is 9561278161.

It is a weak prime.

It is an emirp because it is prime and its reverse (9561278161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1618721659 - 2²¹ = 1616624507 is a prime.

It is not a weakly prime, because it can be changed into another prime (1618721609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 809360829 + 809360830.

It is an arithmetic number, because the mean of its divisors is an integer number (809360830).

Almost surely, 2^1618721659 is an apocalyptic number.

1618721659 is a deficient number, since it is larger than the sum of its proper divisors (1).

1618721659 is an equidigital number, since it uses as much as digits as its factorization.

1618721659 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 46.

The square root of 1618721659 is about 40233.3401422253. The cubic root of 1618721659 is about 1174.1512890944.

The spelling of 1618721659 in words is "one billion, six hundred eighteen million, seven hundred twenty-one thousand, six hundred fifty-nine".