20636649840 has 160 divisors (see below), whose sum is σ = 65242824192. Its totient is φ = 5394816000.

The previous prime is 20636649829. The next prime is 20636649853. The reversal of 20636649840 is 4894663602.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 20636649840.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3080895 + ... + 3087585.

Almost surely, 2^20636649840 is an apocalyptic number.

20636649840 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 20636649840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32621412096).

20636649840 is an abundant number, since it is smaller than the sum of its proper divisors (44606174352).

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

20636649840 is a wasteful number, since it uses less digits than its factorization.

20636649840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6959 (or 6953 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 48.

The spelling of 20636649840 in words is "twenty billion, six hundred thirty-six million, six hundred forty-nine thousand, eight hundred forty".