20991339 has 16 divisors (see below), whose sum is σ = 31687200. Its totient is φ = 13729248.

The previous prime is 20991323. The next prime is 20991359. The reversal of 20991339 is 93319902.

It is not a de Polignac number, because 20991339 - 2⁴ = 20991323 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20991319) by changing a digit.

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, 5904 + ... + 8765.

It is an arithmetic number, because the mean of its divisors is an integer number (1980450).

Almost surely, 2^20991339 is an apocalyptic number.

20991339 is a deficient number, since it is larger than the sum of its proper divisors (10695861).

20991339 is a wasteful number, since it uses less digits than its factorization.

20991339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14731 (or 14725 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 36.

The square root of 20991339 is about 4581.6306049266. The cubic root of 20991339 is about 275.8544837841.

The spelling of 20991339 in words is "twenty million, nine hundred ninety-one thousand, three hundred thirty-nine".