21364830 has 64 divisors (see below), whose sum is σ = 58086720. Its totient is φ = 5586048.

The previous prime is 21364817. The next prime is 21364841. The reversal of 21364830 is 3846312.

21364830 = 206² + 207² + ... + 417².

It is a happy number.

21364830 is a `hidden beast` number, since 2 + 13 + 648 + 3 + 0 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21364794 and 21364803.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13564 + ... + 15056.

It is an arithmetic number, because the mean of its divisors is an integer number (907605).

Almost surely, 2^21364830 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21364830, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29043360).

21364830 is an abundant number, since it is smaller than the sum of its proper divisors (36721890).

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

21364830 is a wasteful number, since it uses less digits than its factorization.

21364830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1562 (or 1556 counting only the distinct ones).

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

The square root of 21364830 is about 4622.2105101347. The cubic root of 21364830 is about 277.4809336791.

The spelling of 21364830 in words is "twenty-one million, three hundred sixty-four thousand, eight hundred thirty".