21642930 has 64 divisors (see below), whose sum is σ = 58579200. Its totient is φ = 5685120.

The previous prime is 21642923. The next prime is 21642937. The reversal of 21642930 is 3924612.

It is an interprime number because it is at equal distance from previous prime (21642923) and next prime (21642937).

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 = 21642894 and 21642903.

It is not an unprimeable number, because it can be changed into a prime (21642937) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 18606 + ... + 19734.

It is an arithmetic number, because the mean of its divisors is an integer number (915300).

Almost surely, 2^21642930 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21642930, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29289600).

21642930 is an abundant number, since it is smaller than the sum of its proper divisors (36936270).

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

21642930 is a wasteful number, since it uses less digits than its factorization.

21642930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1216 (or 1210 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21642930 is about 4652.1962555335. The cubic root of 21642930 is about 278.6797110743.

The spelling of 21642930 in words is "twenty-one million, six hundred forty-two thousand, nine hundred thirty".