21547237530 has 128 divisors (see below), whose sum is σ = 63788433408. Its totient is φ = 4536145152.

The previous prime is 21547237513. The next prime is 21547237531. The reversal of 21547237530 is 3573274512.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21547237531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1255467 + ... + 1272513.

It is an arithmetic number, because the mean of its divisors is an integer number (498347136).

Almost surely, 2^21547237530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21547237530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31894216704).

21547237530 is an abundant number, since it is smaller than the sum of its proper divisors (42241195878).

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

21547237530 is a wasteful number, since it uses less digits than its factorization.

21547237530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17540.

The product of its (nonzero) digits is 176400, while the sum is 39.

The spelling of 21547237530 in words is "twenty-one billion, five hundred forty-seven million, two hundred thirty-seven thousand, five hundred thirty".