1020815640 has 192 divisors, whose sum is σ = 3634394400. Its totient is φ = 246951936.

The previous prime is 1020815617. The next prime is 1020815659. The reversal of 1020815640 is 465180201.

1020815640 is a `hidden beast` number, since 1 + 0 + 2 + 0 + 8 + 15 + 640 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 274272 + ... + 277968.

Almost surely, 2^1020815640 is an apocalyptic number.

1020815640 is a gapful number since it is divisible by the number (10) 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 1020815640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1817197200).

1020815640 is an abundant number, since it is smaller than the sum of its proper divisors (2613578760).

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

1020815640 is a wasteful number, since it uses less digits than its factorization.

1020815640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3786 (or 3779 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 1020815640 is about 31950.2056331411. The cubic root of 1020815640 is about 1006.8909523693.

Adding to 1020815640 its reverse (465180201), we get a palindrome (1485995841).

The spelling of 1020815640 in words is "one billion, twenty million, eight hundred fifteen thousand, six hundred forty".