21436380 has 192 divisors, whose sum is σ = 78382080. Its totient is φ = 4762368.

The previous prime is 21436379. The next prime is 21436397. The reversal of 21436380 is 8363412.

It is a happy number.

21436380 is a `hidden beast` number, since 21 + 4 + 3 + 638 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 200287 + ... + 200393.

It is an arithmetic number, because the mean of its divisors is an integer number (408240).

Almost surely, 2^21436380 is an apocalyptic number.

21436380 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 21436380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39191040).

21436380 is an abundant number, since it is smaller than the sum of its proper divisors (56945700).

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

21436380 is a wasteful number, since it uses less digits than its factorization.

21436380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21436380 is about 4629.9438441519. The cubic root of 21436380 is about 277.7903462165.

Adding to 21436380 its reverse (8363412), we get a palindrome (29799792).

The spelling of 21436380 in words is "twenty-one million, four hundred thirty-six thousand, three hundred eighty".