21628771825 has 12 divisors (see below), whose sum is σ = 27012628720. Its totient is φ = 17178532560.

The previous prime is 21628771811. The next prime is 21628771831. The reversal of 21628771825 is 52817782612.

It is a happy number.

It is not a de Polignac number, because 21628771825 - 2¹³ = 21628763633 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3108579 + ... + 3115528.

Almost surely, 2^21628771825 is an apocalyptic number.

21628771825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21628771825 is a deficient number, since it is larger than the sum of its proper divisors (5383856895).

21628771825 is a wasteful number, since it uses less digits than its factorization.

21628771825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6224256 (or 6224251 counting only the distinct ones).

The product of its digits is 752640, while the sum is 49.

The spelling of 21628771825 in words is "twenty-one billion, six hundred twenty-eight million, seven hundred seventy-one thousand, eight hundred twenty-five".