21487830 has 128 divisors (see below), whose sum is σ = 67350528. Its totient is φ = 4257792.

The previous prime is 21487783. The next prime is 21487891. The reversal of 21487830 is 3878412.

It is a junction number, because it is equal to n+sod(n) for n = 21487791 and 21487800.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 46179 + ... + 46641.

It is an arithmetic number, because the mean of its divisors is an integer number (526176).

Almost surely, 2^21487830 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21487830, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33675264).

21487830 is an abundant number, since it is smaller than the sum of its proper divisors (45862698).

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

21487830 is a wasteful number, since it uses less digits than its factorization.

21487830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510.

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 21487830 is about 4635.4967371362. The cubic root of 21487830 is about 278.0124125369.

The spelling of 21487830 in words is "twenty-one million, four hundred eighty-seven thousand, eight hundred thirty".