20897993 has 2 divisors, whose sum is σ = 20897994. Its totient is φ = 20897992.

The previous prime is 20897983. The next prime is 20898041. The reversal of 20897993 is 39979802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20675209 + 222784 = 4547^2 + 472^2 .

It is a cyclic number.

It is not a de Polignac number, because 20897993 - 2²² = 16703689 is a prime.

It is a super-2 number, since 2×20897993² = 873452222856098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20897923) by changing a digit.

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 as a sum of consecutive naturals, namely, 10448996 + 10448997.

It is an arithmetic number, because the mean of its divisors is an integer number (10448997).

Almost surely, 2^20897993 is an apocalyptic number.

It is an amenable number.

20897993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20897993 is an equidigital number, since it uses as much as digits as its factorization.

20897993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 244944, while the sum is 47.

The square root of 20897993 is about 4571.4322700878. The cubic root of 20897993 is about 275.4449787630. Note that the first 3 decimals are identical.

It can be divided in two parts, 2089799 and 3, that added together give a palindrome (2089802).

The spelling of 20897993 in words is "twenty million, eight hundred ninety-seven thousand, nine hundred ninety-three".