20991582 has 32 divisors (see below), whose sum is σ = 46870560. Its totient is φ = 6963840.

The previous prime is 20991577. The next prime is 20991601. The reversal of 20991582 is 28519902.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12208 + ... + 13820.

It is an arithmetic number, because the mean of its divisors is an integer number (1464705).

Almost surely, 2^20991582 is an apocalyptic number.

20991582 is an abundant number, since it is smaller than the sum of its proper divisors (25878978).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20991582 is a wasteful number, since it uses less digits than its factorization.

20991582 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1865 (or 1859 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 20991582 is about 4581.6571237927. The cubic root of 20991582 is about 275.8555482291.

The spelling of 20991582 in words is "twenty million, nine hundred ninety-one thousand, five hundred eighty-two".