815726640 has 80 divisors (see below), whose sum is σ = 2677516128. Its totient is φ = 204730368.

The previous prime is 815726609. The next prime is 815726647. The reversal of 815726640 is 46627518.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (815726647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 95887 + ... + 104046.

Almost surely, 2^815726640 is an apocalyptic number.

815726640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

815726640 is an abundant number, since it is smaller than the sum of its proper divisors (1861789488).

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

815726640 is a wasteful number, since it uses less digits than its factorization.

815726640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199966 (or 199960 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 815726640 is about 28560.9285563337. The cubic root of 815726640 is about 934.3613853417.

The spelling of 815726640 in words is "eight hundred fifteen million, seven hundred twenty-six thousand, six hundred forty".