20691288 has 80 divisors (see below), whose sum is σ = 59590080. Its totient is φ = 6702912.

The previous prime is 20691287. The next prime is 20691289. The reversal of 20691288 is 88219602.

It is an interprime number because it is at equal distance from previous prime (20691287) and next prime (20691289).

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 (20691287) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 23545 + ... + 24407.

It is an arithmetic number, because the mean of its divisors is an integer number (744876).

Almost surely, 2^20691288 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 20691288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29795040).

20691288 is an abundant number, since it is smaller than the sum of its proper divisors (38898792).

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

20691288 is a wasteful number, since it uses less digits than its factorization.

20691288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 918 (or 905 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 20691288 is about 4548.7677452251. The cubic root of 20691288 is about 274.5338129090.

The spelling of 20691288 in words is "twenty million, six hundred ninety-one thousand, two hundred eighty-eight".