21236543220 has 48 divisors (see below), whose sum is σ = 59592512448. Its totient is φ = 5650679040.

The previous prime is 21236543189. The next prime is 21236543221. The reversal of 21236543220 is 2234563212.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21236543221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 359826 + ... + 414665.

It is an arithmetic number, because the mean of its divisors is an integer number (1241510676).

Almost surely, 2^21236543220 is an apocalyptic number.

21236543220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21236543220 is an abundant number, since it is smaller than the sum of its proper divisors (38355969228).

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

21236543220 is a wasteful number, since it uses less digits than its factorization.

21236543220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 774960 (or 774958 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 30.

The spelling of 21236543220 in words is "twenty-one billion, two hundred thirty-six million, five hundred forty-three thousand, two hundred twenty".