20986971 has 16 divisors (see below), whose sum is σ = 29492736. Its totient is φ = 13248576.

The previous prime is 20986943. The next prime is 20986991. The reversal of 20986971 is 17968902.

It is not a de Polignac number, because 20986971 - 2¹⁸ = 20724827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20986921) 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, 5631 + ... + 8583.

It is an arithmetic number, because the mean of its divisors is an integer number (1843296).

Almost surely, 2^20986971 is an apocalyptic number.

20986971 is a deficient number, since it is larger than the sum of its proper divisors (8505765).

20986971 is a wasteful number, since it uses less digits than its factorization.

20986971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3082.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 20986971 is about 4581.1538939442. The cubic root of 20986971 is about 275.8353486546.

The spelling of 20986971 in words is "twenty million, nine hundred eighty-six thousand, nine hundred seventy-one".