28215385640 has 64 divisors (see below), whose sum is σ = 68867260560. Its totient is φ = 10341918720.

The previous prime is 28215385633. The next prime is 28215385691. The reversal of 28215385640 is 4658351282.

It can be written as a sum of positive squares in 8 ways, for example, as 9004871236 + 19210514404 = 94894^2 + 138602^2 .

It is a super-2 number, since 2×28215385640² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 28215385591 and 28215385600.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 126791 + ... + 269270.

Almost surely, 2^28215385640 is an apocalyptic number.

28215385640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28215385640 is an abundant number, since it is smaller than the sum of its proper divisors (40651874920).

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

28215385640 is a wasteful number, since it uses less digits than its factorization.

28215385640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396222 (or 396218 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 44.

The spelling of 28215385640 in words is "twenty-eight billion, two hundred fifteen million, three hundred eighty-five thousand, six hundred forty".