20897947 has 16 divisors (see below), whose sum is σ = 25477632. Its totient is φ = 16732800.

The previous prime is 20897923. The next prime is 20897969. The reversal of 20897947 is 74979802.

It is not a de Polignac number, because 20897947 - 2⁷ = 20897819 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20897897 and 20897906.

It is not an unprimeable number, because it can be changed into a prime (20897917) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17388 + ... + 18550.

It is an arithmetic number, because the mean of its divisors is an integer number (1592352).

Almost surely, 2^20897947 is an apocalyptic number.

20897947 is a deficient number, since it is larger than the sum of its proper divisors (4579685).

20897947 is a wasteful number, since it uses less digits than its factorization.

20897947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1338.

The product of its (nonzero) digits is 254016, while the sum is 46.

The square root of 20897947 is about 4571.4272388391. The cubic root of 20897947 is about 275.4447766626. Note that the first 3 decimals are identical.

The spelling of 20897947 in words is "twenty million, eight hundred ninety-seven thousand, nine hundred forty-seven".