1981564 has 24 divisors (see below), whose sum is σ = 3810240. Its totient is φ = 896064.

The previous prime is 1981547. The next prime is 1981583. The reversal of 1981564 is 4651891.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2397 + ... + 3115.

It is an arithmetic number, because the mean of its divisors is an integer number (158760).

2^1981564 is an apocalyptic number.

It is an amenable number.

1981564 is a deficient number, since it is larger than the sum of its proper divisors (1828676).

1981564 is a wasteful number, since it uses less digits than its factorization.

1981564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 789 (or 787 counting only the distinct ones).

The product of its digits is 8640, while the sum is 34.

The square root of 1981564 is about 1407.6803614457. The cubic root of 1981564 is about 125.6037775920.

The spelling of 1981564 in words is "one million, nine hundred eighty-one thousand, five hundred sixty-four".