21286645380 has 1152 divisors, whose sum is σ = 92802318336. Its totient is φ = 3807129600.

The previous prime is 21286645361. The next prime is 21286645433. The reversal of 21286645380 is 8354668212.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 206666409 + ... + 206666511.

It is an arithmetic number, because the mean of its divisors is an integer number (80557568).

Almost surely, 2^21286645380 is an apocalyptic number.

21286645380 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 21286645380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46401159168).

21286645380 is an abundant number, since it is smaller than the sum of its proper divisors (71515672956).

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

21286645380 is a wasteful number, since it uses less digits than its factorization.

21286645380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217 (or 212 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

It can be divided in two parts, 21286 and 645380, that added together give a palindrome (666666).

The spelling of 21286645380 in words is "twenty-one billion, two hundred eighty-six million, six hundred forty-five thousand, three hundred eighty".