1617991 has 4 divisors (see below), whose sum is σ = 1629000. Its totient is φ = 1606984.

The previous prime is 1617989. The next prime is 1618003. The reversal of 1617991 is 1997161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1617991 - 2¹ = 1617989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1617971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5281 + ... + 5578.

It is an arithmetic number, because the mean of its divisors is an integer number (407250).

2^1617991 is an apocalyptic number.

1617991 is a deficient number, since it is larger than the sum of its proper divisors (11009).

1617991 is a wasteful number, since it uses less digits than its factorization.

1617991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11008.

The product of its digits is 3402, while the sum is 34.

The square root of 1617991 is about 1272.0027515694. The cubic root of 1617991 is about 117.3974599603.

The spelling of 1617991 in words is "one million, six hundred seventeen thousand, nine hundred ninety-one".