20969640 has 96 divisors (see below), whose sum is σ = 70387200. Its totient is φ = 5408640.

The previous prime is 20969623. The next prime is 20969677. The reversal of 20969640 is 4696902.

20969640 is a `hidden beast` number, since 2 + 0 + 9 + 6 + 9 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 20969595 and 20969604.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10221 + ... + 12099.

It is an arithmetic number, because the mean of its divisors is an integer number (733200).

Almost surely, 2^20969640 is an apocalyptic number.

20969640 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 20969640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35193600).

20969640 is an abundant number, since it is smaller than the sum of its proper divisors (49417560).

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

20969640 is a wasteful number, since it uses less digits than its factorization.

20969640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1927 (or 1920 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 20969640 is about 4579.2619492665. The cubic root of 20969640 is about 275.7593996457.

It can be divided in two parts, 20969 and 640, that added together give a square (21609 = 147²).

The spelling of 20969640 in words is "twenty million, nine hundred sixty-nine thousand, six hundred forty".