20966640 has 80 divisors (see below), whose sum is σ = 65472000. Its totient is φ = 5550336.

The previous prime is 20966611. The next prime is 20966651. The reversal of 20966640 is 4666902.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47541 + ... + 47979.

It is an arithmetic number, because the mean of its divisors is an integer number (818400).

Almost surely, 2^20966640 is an apocalyptic number.

20966640 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 20966640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32736000).

20966640 is an abundant number, since it is smaller than the sum of its proper divisors (44505360).

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

20966640 is a wasteful number, since it uses less digits than its factorization.

20966640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 20966640 is about 4578.9343738473. The cubic root of 20966640 is about 275.7462486068.

The spelling of 20966640 in words is "twenty million, nine hundred sixty-six thousand, six hundred forty".