21247170400 has 72 divisors (see below), whose sum is σ = 51900053184. Its totient is φ = 8493888000.

The previous prime is 21247170389. The next prime is 21247170407. The reversal of 21247170400 is 407174212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247170407) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 1553994 + ... + 1567606.

It is an arithmetic number, because the mean of its divisors is an integer number (720834072).

Almost surely, 2^21247170400 is an apocalyptic number.

21247170400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21247170400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25950026592).

21247170400 is an abundant number, since it is smaller than the sum of its proper divisors (30652882784).

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

21247170400 is a wasteful number, since it uses less digits than its factorization.

21247170400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15584 (or 15571 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 28.

The spelling of 21247170400 in words is "twenty-one billion, two hundred forty-seven million, one hundred seventy thousand, four hundred".