20906940 has 96 divisors (see below), whose sum is σ = 62899200. Its totient is φ = 5170176.

The previous prime is 20906939. The next prime is 20906969. The reversal of 20906940 is 4960902.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20906898 and 20906907.

It is a congruent number.

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, 104961 + ... + 105159.

It is an arithmetic number, because the mean of its divisors is an integer number (655200).

Almost surely, 2^20906940 is an apocalyptic number.

20906940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20906940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31449600).

20906940 is an abundant number, since it is smaller than the sum of its proper divisors (41992260).

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

20906940 is a wasteful number, since it uses less digits than its factorization.

20906940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331 (or 329 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 20906940 is about 4572.4107427046. The cubic root of 20906940 is about 275.4842816539.

The spelling of 20906940 in words is "twenty million, nine hundred six thousand, nine hundred forty".