1998900857 has 2 divisors, whose sum is σ = 1998900858. Its totient is φ = 1998900856.

The previous prime is 1998900821. The next prime is 1998900889. The reversal of 1998900857 is 7580098991.

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., 1270494736 + 728406121 = 35644^2 + 26989^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998900857 - 2⁶ = 1998900793 is a prime.

It is a super-2 number, since 2×1998900857² = 7991209272230668898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1998900257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999450428 + 999450429.

It is an arithmetic number, because the mean of its divisors is an integer number (999450429).

Almost surely, 2^1998900857 is an apocalyptic number.

It is an amenable number.

1998900857 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998900857 is an equidigital number, since it uses as much as digits as its factorization.

1998900857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1632960, while the sum is 56.

The square root of 1998900857 is about 44709.0690688142. The cubic root of 1998900857 is about 1259.6902020335.

The spelling of 1998900857 in words is "one billion, nine hundred ninety-eight million, nine hundred thousand, eight hundred fifty-seven".