21728666475 has 288 divisors, whose sum is σ = 45509587200. Its totient is φ = 10124352000.

The previous prime is 21728666471. The next prime is 21728666483. The reversal of 21728666475 is 57466682712.

It is a happy number.

It is not a de Polignac number, because 21728666475 - 2² = 21728666471 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21728666471) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 505317804 + ... + 505317846.

It is an arithmetic number, because the mean of its divisors is an integer number (158019400).

Almost surely, 2^21728666475 is an apocalyptic number.

21728666475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21728666475 is an abundant number, since it is smaller than the sum of its proper divisors (23780920725).

21728666475 is a wasteful number, since it uses less digits than its factorization.

21728666475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184 (or 142 counting only the distinct ones).

The product of its digits is 6773760, while the sum is 54.

The spelling of 21728666475 in words is "twenty-one billion, seven hundred twenty-eight million, six hundred sixty-six thousand, four hundred seventy-five".