20910906 has 64 divisors (see below), whose sum is σ = 49680000. Its totient is φ = 6500736.

The previous prime is 20910893. The next prime is 20910913. The reversal of 20910906 is 60901902.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 20910906.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 91200 + ... + 91428.

It is an arithmetic number, because the mean of its divisors is an integer number (776250).

Almost surely, 2^20910906 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20910906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24840000).

20910906 is an abundant number, since it is smaller than the sum of its proper divisors (28769094).

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

20910906 is a wasteful number, since it uses less digits than its factorization.

20910906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348 (or 342 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 20910906 is about 4572.8444102112. The cubic root of 20910906 is about 275.5017001376.

The spelling of 20910906 in words is "twenty million, nine hundred ten thousand, nine hundred six".