20537640 has 96 divisors (see below), whose sum is σ = 67602600. Its totient is φ = 5406720.

The previous prime is 20537633. The next prime is 20537653. The reversal of 20537640 is 4673502.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 17489124 + 3048516 = 4182^2 + 1746^2 .

It is a congruent number.

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, 31720 + ... + 32360.

Almost surely, 2^20537640 is an apocalyptic number.

20537640 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 20537640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33801300).

20537640 is an abundant number, since it is smaller than the sum of its proper divisors (47064960).

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

20537640 is a wasteful number, since it uses less digits than its factorization.

20537640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 747 (or 740 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 27.

The square root of 20537640 is about 4531.8473054594. The cubic root of 20537640 is about 273.8525855591.

The spelling of 20537640 in words is "twenty million, five hundred thirty-seven thousand, six hundred forty".