21409475250 has 128 divisors (see below), whose sum is σ = 56950013952. Its totient is φ = 5344574400.

The previous prime is 21409475209. The next prime is 21409475251. The reversal of 21409475250 is 5257490412.

It is a junction number, because it is equal to n+sod(n) for n = 21409475199 and 21409475208.

It is not an unprimeable number, because it can be changed into a prime (21409475251) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 797547 + ... + 823953.

It is an arithmetic number, because the mean of its divisors is an integer number (444921984).

Almost surely, 2^21409475250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21409475250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28475006976).

21409475250 is an abundant number, since it is smaller than the sum of its proper divisors (35540538702).

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

21409475250 is a wasteful number, since it uses less digits than its factorization.

21409475250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26497 (or 26487 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 39.

The spelling of 21409475250 in words is "twenty-one billion, four hundred nine million, four hundred seventy-five thousand, two hundred fifty".