20997187 has 2 divisors, whose sum is σ = 20997188. Its totient is φ = 20997186.

The previous prime is 20997181. The next prime is 20997211. The reversal of 20997187 is 78179902.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20997187 - 2⁷ = 20997059 is a prime.

It is not a weakly prime, because it can be changed into another prime (20997181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10498593 + 10498594.

It is an arithmetic number, because the mean of its divisors is an integer number (10498594).

Almost surely, 2^20997187 is an apocalyptic number.

20997187 is a deficient number, since it is larger than the sum of its proper divisors (1).

20997187 is an equidigital number, since it uses as much as digits as its factorization.

20997187 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 20997187 is about 4582.2687612143. The cubic root of 20997187 is about 275.8800982726.

The spelling of 20997187 in words is "twenty million, nine hundred ninety-seven thousand, one hundred eighty-seven".