1599917981 has 2 divisors, whose sum is σ = 1599917982. Its totient is φ = 1599917980.

The previous prime is 1599917953. The next prime is 1599917989. The reversal of 1599917981 is 1897199951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1555908025 + 44009956 = 39445^2 + 6634^2 .

It is a cyclic number.

It is not a de Polignac number, because 1599917981 - 2²² = 1595723677 is a prime.

It is a super-2 number, since 2×1599917981² = 5119475091854232722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1599917981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1599917989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 799958990 + 799958991.

It is an arithmetic number, because the mean of its divisors is an integer number (799958991).

Almost surely, 2^1599917981 is an apocalyptic number.

It is an amenable number.

1599917981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1599917981 is an equidigital number, since it uses as much as digits as its factorization.

1599917981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1837080, while the sum is 59.

The square root of 1599917981 is about 39998.9747493608. The cubic root of 1599917981 is about 1169.5871095261.

The spelling of 1599917981 in words is "one billion, five hundred ninety-nine million, nine hundred seventeen thousand, nine hundred eighty-one".