20840688 has 120 divisors (see below), whose sum is σ = 64995840. Its totient is φ = 6180480.

The previous prime is 20840683. The next prime is 20840707. The reversal of 20840688 is 88604802.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20840683) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 93345 + ... + 93567.

It is an arithmetic number, because the mean of its divisors is an integer number (541632).

Almost surely, 2^20840688 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20840688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32497920).

20840688 is an abundant number, since it is smaller than the sum of its proper divisors (44155152).

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

20840688 is a wasteful number, since it uses less digits than its factorization.

20840688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 307 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The square root of 20840688 is about 4565.1602381516. The cubic root of 20840688 is about 275.1929796974.

It can be divided in two parts, 20840 and 688, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 20840688 in words is "twenty million, eight hundred forty thousand, six hundred eighty-eight".