21547003828 has 72 divisors (see below), whose sum is σ = 45998555400. Its totient is φ = 8793695232.

The previous prime is 21547003801. The next prime is 21547003837. The reversal of 21547003828 is 82830074512.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9874794384 + 11672209444 = 99372^2 + 108038^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 388968 + ... + 440896.

It is an arithmetic number, because the mean of its divisors is an integer number (638868825).

Almost surely, 2^21547003828 is an apocalyptic number.

21547003828 is a gapful number since it is divisible by the number (28) 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 21547003828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22999277700).

21547003828 is an abundant number, since it is smaller than the sum of its proper divisors (24451551572).

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

21547003828 is a wasteful number, since it uses less digits than its factorization.

21547003828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52049 (or 52040 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 40.

The spelling of 21547003828 in words is "twenty-one billion, five hundred forty-seven million, three thousand, eight hundred twenty-eight".