1997807849 has 2 divisors, whose sum is σ = 1997807850. Its totient is φ = 1997807848.

The previous prime is 1997807837. The next prime is 1997807893. The reversal of 1997807849 is 9487087991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1281282025 + 716525824 = 35795^2 + 26768^2 .

It is a cyclic number.

It is not a de Polignac number, because 1997807849 - 2²⁰ = 1996759273 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1997807791 and 1997807800.

It is not a weakly prime, because it can be changed into another prime (1997807549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 998903924 + 998903925.

It is an arithmetic number, because the mean of its divisors is an integer number (998903925).

Almost surely, 2^1997807849 is an apocalyptic number.

It is an amenable number.

1997807849 is a deficient number, since it is larger than the sum of its proper divisors (1).

1997807849 is an equidigital number, since it uses as much as digits as its factorization.

1997807849 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9144576, while the sum is 62.

The square root of 1997807849 is about 44696.8438371212. The cubic root of 1997807849 is about 1259.4605587446.

The spelling of 1997807849 in words is "one billion, nine hundred ninety-seven million, eight hundred seven thousand, eight hundred forty-nine".