20421899 has 2 divisors, whose sum is σ = 20421900. Its totient is φ = 20421898.

The previous prime is 20421883. The next prime is 20421937. The reversal of 20421899 is 99812402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20421899 - 2⁴ = 20421883 is a prime.

It is not a weakly prime, because it can be changed into another prime (20421859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210949 + 10210950.

It is an arithmetic number, because the mean of its divisors is an integer number (10210950).

Almost surely, 2^20421899 is an apocalyptic number.

20421899 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421899 is an equidigital number, since it uses as much as digits as its factorization.

20421899 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 20421899 is about 4519.0595260519. The cubic root of 20421899 is about 273.3371790390.

The spelling of 20421899 in words is "twenty million, four hundred twenty-one thousand, eight hundred ninety-nine".