21364550420 has 72 divisors (see below), whose sum is σ = 47871038040. Its totient is φ = 8007505920.

The previous prime is 21364550407. The next prime is 21364550443. The reversal of 21364550420 is 2405546312.

It can be written as a sum of positive squares in 12 ways, for example, as 44462224 + 21320088196 = 6668^2 + 146014^2 .

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, 1315550 + ... + 1331690.

Almost surely, 2^21364550420 is an apocalyptic number.

21364550420 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 21364550420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23935519020).

21364550420 is an abundant number, since it is smaller than the sum of its proper divisors (26506487620).

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

21364550420 is a wasteful number, since it uses less digits than its factorization.

21364550420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16413 (or 16394 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 32.

The spelling of 21364550420 in words is "twenty-one billion, three hundred sixty-four million, five hundred fifty thousand, four hundred twenty".