21815800254 has 16 divisors (see below), whose sum is σ = 48479556240. Its totient is φ = 7271933400.

The previous prime is 21815800243. The next prime is 21815800297. The reversal of 21815800254 is 45200851812.

21815800254 is a `hidden beast` number, since 21 + 8 + 1 + 580 + 0 + 2 + 54 = 666.

21815800254 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 201998097 + ... + 201998204.

It is an arithmetic number, because the mean of its divisors is an integer number (3029972265).

Almost surely, 2^21815800254 is an apocalyptic number.

21815800254 is an abundant number, since it is smaller than the sum of its proper divisors (26663755986).

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

21815800254 is a wasteful number, since it uses less digits than its factorization.

21815800254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403996312 (or 403996306 counting only the distinct ones).

The product of its (nonzero) digits is 25600, while the sum is 36.

The spelling of 21815800254 in words is "twenty-one billion, eight hundred fifteen million, eight hundred thousand, two hundred fifty-four".