21929628 has 48 divisors (see below), whose sum is σ = 59318784. Its totient is φ = 6175680.

The previous prime is 21929623. The next prime is 21929639. The reversal of 21929628 is 82692912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21929623) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4126 + ... + 7802.

It is an arithmetic number, because the mean of its divisors is an integer number (1235808).

Almost surely, 2^21929628 is an apocalyptic number.

21929628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21929628, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29659392).

21929628 is an abundant number, since it is smaller than the sum of its proper divisors (37389156).

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

21929628 is a wasteful number, since it uses less digits than its factorization.

21929628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3762 (or 3760 counting only the distinct ones).

The product of its digits is 31104, while the sum is 39.

The square root of 21929628 is about 4682.9080708466. The cubic root of 21929628 is about 279.9048486211.

It can be divided in two parts, 2 and 1929628, that added together give a triangular number (1929630 = T₁₉₆₄).

The spelling of 21929628 in words is "twenty-one million, nine hundred twenty-nine thousand, six hundred twenty-eight".