1981637 has 8 divisors (see below), whose sum is σ = 2283072. Its totient is φ = 1684800.

The previous prime is 1981631. The next prime is 1981649. The reversal of 1981637 is 7361891.

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 1981637 - 2⁴ = 1981621 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1981597 and 1981606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981631) 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, 164 + ... + 1997.

It is an arithmetic number, because the mean of its divisors is an integer number (285384).

2^1981637 is an apocalyptic number.

It is an amenable number.

1981637 is a deficient number, since it is larger than the sum of its proper divisors (301435).

1981637 is a wasteful number, since it uses less digits than its factorization.

1981637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2299.

The product of its digits is 9072, while the sum is 35.

The square root of 1981637 is about 1407.7062903887. The cubic root of 1981637 is about 125.6053199702.

The spelling of 1981637 in words is "one million, nine hundred eighty-one thousand, six hundred thirty-seven".