21219930 has 48 divisors (see below), whose sum is σ = 55606824. Its totient is φ = 5614080.

The previous prime is 21219929. The next prime is 21219937. The reversal of 21219930 is 3991212.

It can be written as a sum of positive squares in 4 ways, for example, as 19421649 + 1798281 = 4407^2 + 1341^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21219894 and 21219903.

It is not an unprimeable number, because it can be changed into a prime (21219937) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11470 + ... + 13190.

Almost surely, 2^21219930 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21219930, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27803412).

21219930 is an abundant number, since it is smaller than the sum of its proper divisors (34386894).

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

21219930 is a wasteful number, since it uses less digits than its factorization.

21219930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1871 (or 1868 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21219930 is about 4606.5095245750. The cubic root of 21219930 is about 276.8522021256.

The spelling of 21219930 in words is "twenty-one million, two hundred nineteen thousand, nine hundred thirty".