1821864997 has 2 divisors, whose sum is σ = 1821864998. Its totient is φ = 1821864996.

The previous prime is 1821864949. The next prime is 1821865007. The reversal of 1821864997 is 7994681281.

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., 1551887236 + 269977761 = 39394^2 + 16431^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1821864997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1821864697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910932498 + 910932499.

It is an arithmetic number, because the mean of its divisors is an integer number (910932499).

Almost surely, 2^1821864997 is an apocalyptic number.

It is an amenable number.

1821864997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821864997 is an equidigital number, since it uses as much as digits as its factorization.

1821864997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1741824, while the sum is 55.

The square root of 1821864997 is about 42683.3105206239. The cubic root of 1821864997 is about 1221.3460456935.

The spelling of 1821864997 in words is "one billion, eight hundred twenty-one million, eight hundred sixty-four thousand, nine hundred ninety-seven".