28370721640 has 16 divisors (see below), whose sum is σ = 63834123780. Its totient is φ = 11348288640.

The previous prime is 28370721637. The next prime is 28370721649. The reversal of 28370721640 is 4612707382.

It can be written as a sum of positive squares in 2 ways, for example, as 27445223556 + 925498084 = 165666^2 + 30422^2 .

It is a Harshad number since it is a multiple of its sum of digits (40), and also a Moran number because the ratio is a prime number: 709268041 = 28370721640 / (2 + 8 + 3 + 7 + 0 + 7 + 2 + 1 + 6 + 4 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 28370721593 and 28370721602.

It is not an unprimeable number, because it can be changed into a prime (28370721649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 354633981 + ... + 354634060.

Almost surely, 2^28370721640 is an apocalyptic number.

28370721640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28370721640 is an abundant number, since it is smaller than the sum of its proper divisors (35463402140).

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

28370721640 is a wasteful number, since it uses less digits than its factorization.

28370721640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 709268052 (or 709268048 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 40.

The spelling of 28370721640 in words is "twenty-eight billion, three hundred seventy million, seven hundred twenty-one thousand, six hundred forty".