20021399 has 2 divisors, whose sum is σ = 20021400. Its totient is φ = 20021398.

The previous prime is 20021387. The next prime is 20021411. The reversal of 20021399 is 99312002.

It is a balanced prime because it is at equal distance from previous prime (20021387) and next prime (20021411).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021399 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20021369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010699 + 10010700.

It is an arithmetic number, because the mean of its divisors is an integer number (10010700).

Almost surely, 2^20021399 is an apocalyptic number.

20021399 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021399 is an equidigital number, since it uses as much as digits as its factorization.

20021399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 20021399 is about 4474.5277963155. The cubic root of 20021399 is about 271.5385368571.

The spelling of 20021399 in words is "twenty million, twenty-one thousand, three hundred ninety-nine".