20809494 has 48 divisors (see below), whose sum is σ = 47902320. Its totient is φ = 6696000.

The previous prime is 20809493. The next prime is 20809553. The reversal of 20809494 is 49490802.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51694 + ... + 52094.

It is an arithmetic number, because the mean of its divisors is an integer number (997965).

Almost surely, 2^20809494 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20809494, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23951160).

20809494 is an abundant number, since it is smaller than the sum of its proper divisors (27092826).

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

20809494 is a wasteful number, since it uses less digits than its factorization.

20809494 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 474 (or 437 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 20809494 is about 4561.7424302562. The cubic root of 20809494 is about 275.0556096907.

The spelling of 20809494 in words is "twenty million, eight hundred nine thousand, four hundred ninety-four".