20420999 has 2 divisors, whose sum is σ = 20421000. Its totient is φ = 20420998.

The previous prime is 20420989. The next prime is 20421013. The reversal of 20420999 is 99902402.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20420999 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20420989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210499 + 10210500.

It is an arithmetic number, because the mean of its divisors is an integer number (10210500).

Almost surely, 2^20420999 is an apocalyptic number.

20420999 is a deficient number, since it is larger than the sum of its proper divisors (1).

20420999 is an equidigital number, since it uses as much as digits as its factorization.

20420999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 20420999 is about 4518.9599467134. The cubic root of 20420999 is about 273.3331636260. Note that the first 3 decimals are identical.

The spelling of 20420999 in words is "twenty million, four hundred twenty thousand, nine hundred ninety-nine".