1981800851 has 2 divisors, whose sum is σ = 1981800852. Its totient is φ = 1981800850.

The previous prime is 1981800817. The next prime is 1981800883. The reversal of 1981800851 is 1580081891.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1981800851 - 2¹⁸ = 1981538707 is a prime.

It is a super-2 number, since 2×1981800851² = 7855069226048648402, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1981800799 and 1981800808.

It is not a weakly prime, because it can be changed into another prime (1981806851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990900425 + 990900426.

It is an arithmetic number, because the mean of its divisors is an integer number (990900426).

Almost surely, 2^1981800851 is an apocalyptic number.

1981800851 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981800851 is an equidigital number, since it uses as much as digits as its factorization.

1981800851 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23040, while the sum is 41.

The square root of 1981800851 is about 44517.4218817757. The cubic root of 1981800851 is about 1256.0878175291.

The spelling of 1981800851 in words is "one billion, nine hundred eighty-one million, eight hundred thousand, eight hundred fifty-one".