20821899 has 16 divisors (see below), whose sum is σ = 31799808. Its totient is φ = 11871552.

The previous prime is 20821897. The next prime is 20821907. The reversal of 20821899 is 99812802.

It is not a de Polignac number, because 20821899 - 2¹ = 20821897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20821897) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12154 + ... + 13760.

It is an arithmetic number, because the mean of its divisors is an integer number (1987488).

Almost surely, 2^20821899 is an apocalyptic number.

20821899 is a deficient number, since it is larger than the sum of its proper divisors (10977909).

20821899 is a wasteful number, since it uses less digits than its factorization.

20821899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2234.

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 20821899 is about 4563.1019055024. The cubic root of 20821899 is about 275.1102544129.

The spelling of 20821899 in words is "twenty million, eight hundred twenty-one thousand, eight hundred ninety-nine".