1986984821 has 2 divisors, whose sum is σ = 1986984822. Its totient is φ = 1986984820.

The previous prime is 1986984809. The next prime is 1986984823. The reversal of 1986984821 is 1284896891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1979004196 + 7980625 = 44486^2 + 2825^2 .

It is a cyclic number.

It is not a de Polignac number, because 1986984821 - 2¹⁸ = 1986722677 is a prime.

Together with 1986984823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1986984823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993492410 + 993492411.

It is an arithmetic number, because the mean of its divisors is an integer number (993492411).

Almost surely, 2^1986984821 is an apocalyptic number.

It is an amenable number.

1986984821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1986984821 is an equidigital number, since it uses as much as digits as its factorization.

1986984821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1990656, while the sum is 56.

The square root of 1986984821 is about 44575.6079150919. The cubic root of 1986984821 is about 1257.1820835870.

The spelling of 1986984821 in words is "one billion, nine hundred eighty-six million, nine hundred eighty-four thousand, eight hundred twenty-one".