20829809 has 16 divisors (see below), whose sum is σ = 27968640. Its totient is φ = 14981760.

The previous prime is 20829749. The next prime is 20829821. The reversal of 20829809 is 90892802.

It is a cyclic number.

It is not a de Polignac number, because 20829809 - 2¹² = 20825713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20829839) 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, 9404 + ... + 11405.

It is an arithmetic number, because the mean of its divisors is an integer number (1748040).

Almost surely, 2^20829809 is an apocalyptic number.

It is an amenable number.

20829809 is a deficient number, since it is larger than the sum of its proper divisors (7138831).

20829809 is a wasteful number, since it uses less digits than its factorization.

20829809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20840.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 20829809 is about 4563.9685581739. The cubic root of 20829809 is about 275.1450870765.

The spelling of 20829809 in words is "twenty million, eight hundred twenty-nine thousand, eight hundred nine".