1931989 has 2 divisors, whose sum is σ = 1931990. Its totient is φ = 1931988.

The previous prime is 1931987. The next prime is 1932001. The reversal of 1931989 is 9891391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1067089 + 864900 = 1033^2 + 930^2 .

It is an emirp because it is prime and its reverse (9891391) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1931989 - 2¹ = 1931987 is a prime.

It is a super-2 number, since 2×1931989² = 7465162992242, which contains 22 as substring.

Together with 1931987, it forms a pair of twin primes.

1931989 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1931983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 965994 + 965995.

It is an arithmetic number, because the mean of its divisors is an integer number (965995).

2^1931989 is an apocalyptic number.

It is an amenable number.

1931989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1931989 is an equidigital number, since it uses as much as digits as its factorization.

1931989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 40.

The square root of 1931989 is about 1389.9600713690. The cubic root of 1931989 is about 124.5474623209.

The spelling of 1931989 in words is "one million, nine hundred thirty-one thousand, nine hundred eighty-nine".