1821987899 has 2 divisors, whose sum is σ = 1821987900. Its totient is φ = 1821987898.

The previous prime is 1821987887. The next prime is 1821987907. The reversal of 1821987899 is 9987891281.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (9987891281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1821987899 - 2¹⁶ = 1821922363 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1821987829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910993949 + 910993950.

It is an arithmetic number, because the mean of its divisors is an integer number (910993950).

Almost surely, 2^1821987899 is an apocalyptic number.

1821987899 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821987899 is an equidigital number, since it uses as much as digits as its factorization.

1821987899 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5225472, while the sum is 62.

The square root of 1821987899 is about 42684.7501925453. The cubic root of 1821987899 is about 1221.3735088510.

The spelling of 1821987899 in words is "one billion, eight hundred twenty-one million, nine hundred eighty-seven thousand, eight hundred ninety-nine".