21865028740 has 24 divisors (see below), whose sum is σ = 46039676760. Its totient is φ = 8722560768.

The previous prime is 21865028707. The next prime is 21865028747. The reversal of 21865028740 is 4782056812.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9796248576 + 12068780164 = 98976^2 + 109858^2 .

It is not an unprimeable number, because it can be changed into a prime (21865028747) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1458025 + ... + 1472944.

It is an arithmetic number, because the mean of its divisors is an integer number (1918319865).

Almost surely, 2^21865028740 is an apocalyptic number.

21865028740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21865028740 is an abundant number, since it is smaller than the sum of its proper divisors (24174648020).

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

21865028740 is a wasteful number, since it uses less digits than its factorization.

21865028740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2931351 (or 2931349 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 43.

The spelling of 21865028740 in words is "twenty-one billion, eight hundred sixty-five million, twenty-eight thousand, seven hundred forty".