21545599025 has 24 divisors (see below), whose sum is σ = 28034009280. Its totient is φ = 16394882240.

The previous prime is 21545598989. The next prime is 21545599027. The reversal of 21545599025 is 52099554512.

It is not a de Polignac number, because 21545599025 - 2⁶ = 21545598961 is a prime.

It is a hoax number, since the sum of its digits (47) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21545599027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1742 + ... + 207591.

It is an arithmetic number, because the mean of its divisors is an integer number (1168083720).

Almost surely, 2^21545599025 is an apocalyptic number.

21545599025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21545599025 is a deficient number, since it is larger than the sum of its proper divisors (6488410255).

21545599025 is a wasteful number, since it uses less digits than its factorization.

21545599025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209545 (or 209540 counting only the distinct ones).

The product of its (nonzero) digits is 810000, while the sum is 47.

The spelling of 21545599025 in words is "twenty-one billion, five hundred forty-five million, five hundred ninety-nine thousand, twenty-five".