1991649 has 8 divisors (see below), whose sum is σ = 2896992. Its totient is φ = 1207040.

The previous prime is 1991641. The next prime is 1991653. The reversal of 1991649 is 9461991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1991649 - 2³ = 1991641 is a prime.

It is an Ulam number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1991641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30144 + ... + 30209.

It is an arithmetic number, because the mean of its divisors is an integer number (362124).

2^1991649 is an apocalyptic number.

It is an amenable number.

1991649 is a deficient number, since it is larger than the sum of its proper divisors (905343).

1991649 is a wasteful number, since it uses less digits than its factorization.

1991649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60367.

The product of its digits is 17496, while the sum is 39.

The square root of 1991649 is about 1411.2579494905. The cubic root of 1991649 is about 125.8165003384.

The spelling of 1991649 in words is "one million, nine hundred ninety-one thousand, six hundred forty-nine".