21629680 has 20 divisors (see below), whose sum is σ = 50289192. Its totient is φ = 8651840.

The previous prime is 21629617. The next prime is 21629687. The reversal of 21629680 is 8692612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21629687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135106 + ... + 135265.

Almost surely, 2^21629680 is an apocalyptic number.

21629680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21629680 is an abundant number, since it is smaller than the sum of its proper divisors (28659512).

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

21629680 is a wasteful number, since it uses less digits than its factorization.

21629680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270384 (or 270378 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 21629680 is about 4650.7719789299. The cubic root of 21629680 is about 278.6228293743.

The spelling of 21629680 in words is "twenty-one million, six hundred twenty-nine thousand, six hundred eighty".