21427680 has 48 divisors (see below), whose sum is σ = 67498704. Its totient is φ = 5713920.

The previous prime is 21427673. The next prime is 21427709. The reversal of 21427680 is 8672412.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 21841 + ... + 22800.

It is an arithmetic number, because the mean of its divisors is an integer number (1406223).

Almost surely, 2^21427680 is an apocalyptic number.

21427680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21427680 is an abundant number, since it is smaller than the sum of its proper divisors (46071024).

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

21427680 is a wasteful number, since it uses less digits than its factorization.

21427680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44659 (or 44651 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21427680 is about 4629.0042125710. The cubic root of 21427680 is about 277.7527605321.

The spelling of 21427680 in words is "twenty-one million, four hundred twenty-seven thousand, six hundred eighty".