21550004125 has 32 divisors (see below), whose sum is σ = 28981461600. Its totient is φ = 15903820800.

The previous prime is 21550004111. The next prime is 21550004129. The reversal of 21550004125 is 52140005512.

It can be written as a sum of positive squares in 16 ways, for example, as 20221693209 + 1328310916 = 142203^2 + 36446^2 .

It is not a de Polignac number, because 21550004125 - 2⁵ = 21550004093 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a self number, because there is not a number n which added to its sum of digits gives 21550004125.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550004129) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3456511 + ... + 3462739.

It is an arithmetic number, because the mean of its divisors is an integer number (905670675).

Almost surely, 2^21550004125 is an apocalyptic number.

21550004125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21550004125 is a deficient number, since it is larger than the sum of its proper divisors (7431457475).

21550004125 is a wasteful number, since it uses less digits than its factorization.

21550004125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8386 (or 8376 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

Adding to 21550004125 its reverse (52140005512), we get a palindrome (73690009637).

The spelling of 21550004125 in words is "twenty-one billion, five hundred fifty million, four thousand, one hundred twenty-five".