21628959657240 has 256 divisors, whose sum is σ = 72367320453120. Its totient is φ = 5135521720320.

The previous prime is 21628959657191. The next prime is 21628959657247. The reversal of 21628959657240 is 4275695982612.

It is a Smith number, since the sum of its digits (66) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21628959657247) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 14118102 + ... + 15574938.

It is an arithmetic number, because the mean of its divisors is an integer number (282684845520).

Almost surely, 2^{21628959657240} is an apocalyptic number.

21628959657240 is a gapful number since it is divisible by the number (20) 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 21628959657240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36183660226560).

21628959657240 is an abundant number, since it is smaller than the sum of its proper divisors (50738360795880).

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

21628959657240 is a wasteful number, since it uses less digits than its factorization.

21628959657240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1457202 (or 1457198 counting only the distinct ones).

The product of its (nonzero) digits is 130636800, while the sum is 66.

The spelling of 21628959657240 in words is "twenty-one trillion, six hundred twenty-eight billion, nine hundred fifty-nine million, six hundred fifty-seven thousand, two hundred forty".