20615538240 has 672 divisors, whose sum is σ = 82934616960. Its totient is φ = 4644864000.

The previous prime is 20615538239. The next prime is 20615538247. The reversal of 20615538240 is 4283551602.

20615538240 is a `hidden beast` number, since 2 + 0 + 61 + 553 + 8 + 2 + 40 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 20615538195 and 20615538204.

It is not an unprimeable number, because it can be changed into a prime (20615538247) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 54394371 + ... + 54394749.

Almost surely, 2^20615538240 is an apocalyptic number.

20615538240 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 20615538240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41467308480).

20615538240 is an abundant number, since it is smaller than the sum of its proper divisors (62319078720).

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

20615538240 is a wasteful number, since it uses less digits than its factorization.

20615538240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 531 (or 518 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

It can be divided in two parts, 20615 and 538240, that added together give a palindrome (558855).

The spelling of 20615538240 in words is "twenty billion, six hundred fifteen million, five hundred thirty-eight thousand, two hundred forty".