1199891989 has 2 divisors, whose sum is σ = 1199891990. Its totient is φ = 1199891988.

The previous prime is 1199891951. The next prime is 1199891993. The reversal of 1199891989 is 9891989911.

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., 752569489 + 447322500 = 27433^2 + 21150^2 .

It is a cyclic number.

It is not a de Polignac number, because 1199891989 - 2¹⁷ = 1199760917 is a prime.

It is a super-2 number, since 2×1199891989² = 2879481570532752242, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1199891989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1199891689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 599945994 + 599945995.

It is an arithmetic number, because the mean of its divisors is an integer number (599945995).

Almost surely, 2^1199891989 is an apocalyptic number.

It is an amenable number.

1199891989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1199891989 is an equidigital number, since it uses as much as digits as its factorization.

1199891989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3779136, while the sum is 64.

The square root of 1199891989 is about 34639.4571117967. The cubic root of 1199891989 is about 1062.6266852219.

The spelling of 1199891989 in words is "one billion, one hundred ninety-nine million, eight hundred ninety-one thousand, nine hundred eighty-nine".