21397714728 has 192 divisors, whose sum is σ = 62907062400. Its totient is φ = 6021388800.

The previous prime is 21397714711. The next prime is 21397714783. The reversal of 21397714728 is 82741779312.

It is a super-2 number, since 2×21397714728² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3263053 + ... + 3269603.

It is an arithmetic number, because the mean of its divisors is an integer number (327640950).

Almost surely, 2^21397714728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21397714728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31453531200).

21397714728 is an abundant number, since it is smaller than the sum of its proper divisors (41509347672).

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

21397714728 is a wasteful number, since it uses less digits than its factorization.

21397714728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6640 (or 6617 counting only the distinct ones).

The product of its digits is 1185408, while the sum is 51.

The spelling of 21397714728 in words is "twenty-one billion, three hundred ninety-seven million, seven hundred fourteen thousand, seven hundred twenty-eight".