21212724260 has 144 divisors (see below), whose sum is σ = 55896778224. Its totient is φ = 6702538752.

The previous prime is 21212724251. The next prime is 21212724289. The reversal of 21212724260 is 6242721212.

It can be written as a sum of positive squares in 8 ways, for example, as 5603720164 + 15609004096 = 74858^2 + 124936^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 11936492 + ... + 11938268.

It is an arithmetic number, because the mean of its divisors is an integer number (388172071).

Almost surely, 2^21212724260 is an apocalyptic number.

21212724260 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 21212724260, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27948389112).

21212724260 is an abundant number, since it is smaller than the sum of its proper divisors (34684053964).

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

21212724260 is a wasteful number, since it uses less digits than its factorization.

21212724260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2750 (or 2741 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 29.

The spelling of 21212724260 in words is "twenty-one billion, two hundred twelve million, seven hundred twenty-four thousand, two hundred sixty".