20809830 has 16 divisors (see below), whose sum is σ = 49943664. Its totient is φ = 5549280.

The previous prime is 20809813. The next prime is 20809847. The reversal of 20809830 is 3890802.

It is an interprime number because it is at equal distance from previous prime (20809813) and next prime (20809847).

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 693661 = 20809830 / (2 + 0 + 8 + 0 + 9 + 8 + 3 + 0).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 346801 + ... + 346860.

It is an arithmetic number, because the mean of its divisors is an integer number (3121479).

Almost surely, 2^20809830 is an apocalyptic number.

20809830 is an abundant number, since it is smaller than the sum of its proper divisors (29133834).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20809830 is a wasteful number, since it uses less digits than its factorization.

20809830 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 693671.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 20809830 is about 4561.7792581404. The cubic root of 20809830 is about 275.0570900756.

The spelling of 20809830 in words is "twenty million, eight hundred nine thousand, eight hundred thirty".