1998615851 has 2 divisors, whose sum is σ = 1998615852. Its totient is φ = 1998615850.

The previous prime is 1998615841. The next prime is 1998615943. The reversal of 1998615851 is 1585168991.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1998615851 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 1998615793 and 1998615802.

It is not a weakly prime, because it can be changed into another prime (1998615841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999307925 + 999307926.

It is an arithmetic number, because the mean of its divisors is an integer number (999307926).

Almost surely, 2^1998615851 is an apocalyptic number.

1998615851 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998615851 is an equidigital number, since it uses as much as digits as its factorization.

1998615851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 777600, while the sum is 53.

The square root of 1998615851 is about 44705.8816152864. The cubic root of 1998615851 is about 1259.6303297410.

The spelling of 1998615851 in words is "one billion, nine hundred ninety-eight million, six hundred fifteen thousand, eight hundred fifty-one".