21929830 has 32 divisors (see below), whose sum is σ = 45015264. Its totient is φ = 7620096.

The previous prime is 21929821. The next prime is 21929849. The reversal of 21929830 is 3892912.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2752 + ... + 7171.

It is an arithmetic number, because the mean of its divisors is an integer number (1406727).

Almost surely, 2^21929830 is an apocalyptic number.

21929830 is an abundant number, since it is smaller than the sum of its proper divisors (23085434).

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

21929830 is a wasteful number, since it uses less digits than its factorization.

21929830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9960.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 21929830 is about 4682.9296385916. The cubic root of 21929830 is about 279.9057080460.

The spelling of 21929830 in words is "twenty-one million, nine hundred twenty-nine thousand, eight hundred thirty".