21798630 has 72 divisors (see below), whose sum is σ = 65943072. Its totient is φ = 4981536.

The previous prime is 21798619. The next prime is 21798631. The reversal of 21798630 is 3689712.

21798630 is a `hidden beast` number, since 2 + 17 + 9 + 8 + 630 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21798631) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1939 + ... + 6881.

It is an arithmetic number, because the mean of its divisors is an integer number (915876).

Almost surely, 2^21798630 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21798630, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32971536).

21798630 is an abundant number, since it is smaller than the sum of its proper divisors (44144442).

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

21798630 is a wasteful number, since it uses less digits than its factorization.

21798630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4970 (or 4960 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21798630 is about 4668.9002987856. The cubic root of 21798630 is about 279.3463921279.

The spelling of 21798630 in words is "twenty-one million, seven hundred ninety-eight thousand, six hundred thirty".