1989961 has 2 divisors, whose sum is σ = 1989962. Its totient is φ = 1989960.

The previous prime is 1989959. The next prime is 1989973. The reversal of 1989961 is 1699891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1863225 + 126736 = 1365^2 + 356^2 .

It is a cyclic number.

It is not a de Polignac number, because 1989961 - 2¹ = 1989959 is a prime.

Together with 1989959, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1989161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 994980 + 994981.

It is an arithmetic number, because the mean of its divisors is an integer number (994981).

2^1989961 is an apocalyptic number.

It is an amenable number.

1989961 is a deficient number, since it is larger than the sum of its proper divisors (1).

1989961 is an equidigital number, since it uses as much as digits as its factorization.

1989961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 43.

The square root of 1989961 is about 1410.6597747154. The cubic root of 1989961 is about 125.7809454991.

The spelling of 1989961 in words is "one million, nine hundred eighty-nine thousand, nine hundred sixty-one".