20617999 has 2 divisors, whose sum is σ = 20618000. Its totient is φ = 20617998.

The previous prime is 20617981. The next prime is 20618011. The reversal of 20617999 is 99971602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20617999 - 2⁷ = 20617871 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20617799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10308999 + 10309000.

It is an arithmetic number, because the mean of its divisors is an integer number (10309000).

Almost surely, 2^20617999 is an apocalyptic number.

20617999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20617999 is an equidigital number, since it uses as much as digits as its factorization.

20617999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 43.

The square root of 20617999 is about 4540.7046809939. The cubic root of 20617999 is about 274.2092945095.

The spelling of 20617999 in words is "twenty million, six hundred seventeen thousand, nine hundred ninety-nine".