1981917 has 24 divisors (see below), whose sum is σ = 3308864. Its totient is φ = 1119744.

The previous prime is 1981901. The next prime is 1981919. The reversal of 1981917 is 7191891.

It is not a de Polignac number, because 1981917 - 2⁴ = 1981901 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981919) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10173 + ... + 10365.

2^1981917 is an apocalyptic number.

It is an amenable number.

1981917 is a deficient number, since it is larger than the sum of its proper divisors (1326947).

1981917 is a wasteful number, since it uses less digits than its factorization.

1981917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369 (or 366 counting only the distinct ones).

The product of its digits is 4536, while the sum is 36.

The square root of 1981917 is about 1407.8057394399. The cubic root of 1981917 is about 125.6112355900.

The spelling of 1981917 in words is "one million, nine hundred eighty-one thousand, nine hundred seventeen".