20694640 has 40 divisors (see below), whose sum is σ = 48434400. Its totient is φ = 8222976.

The previous prime is 20694637. The next prime is 20694647. The reversal of 20694640 is 4649602.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20694647) 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 7 ways as a sum of consecutive naturals, for example, 12586 + ... + 14134.

It is an arithmetic number, because the mean of its divisors is an integer number (1210860).

Almost surely, 2^20694640 is an apocalyptic number.

20694640 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 20694640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24217200).

20694640 is an abundant number, since it is smaller than the sum of its proper divisors (27739760).

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

20694640 is a wasteful number, since it uses less digits than its factorization.

20694640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1729 (or 1723 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 20694640 is about 4549.1361817382. The cubic root of 20694640 is about 274.5486369846.

The spelling of 20694640 in words is "twenty million, six hundred ninety-four thousand, six hundred forty".