21629380 has 24 divisors (see below), whose sum is σ = 46168920. Its totient is φ = 8509440.

The previous prime is 21629371. The next prime is 21629381. The reversal of 21629380 is 8392612.

It can be written as a sum of positive squares in 4 ways, for example, as 248004 + 21381376 = 498^2 + 4624^2 .

It is not an unprimeable number, because it can be changed into a prime (21629381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7645 + ... + 10084.

It is an arithmetic number, because the mean of its divisors is an integer number (1923705).

Almost surely, 2^21629380 is an apocalyptic number.

21629380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21629380 is an abundant number, since it is smaller than the sum of its proper divisors (24539540).

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

21629380 is a wasteful number, since it uses less digits than its factorization.

21629380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17799 (or 17797 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21629380 is about 4650.7397261081. The cubic root of 21629380 is about 278.6215412179.

The spelling of 21629380 in words is "twenty-one million, six hundred twenty-nine thousand, three hundred eighty".