21421580 has 24 divisors (see below), whose sum is σ = 45073392. Its totient is φ = 8551872.

The previous prime is 21421559. The next prime is 21421597. The reversal of 21421580 is 8512412.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17054 + ... + 18266.

It is an arithmetic number, because the mean of its divisors is an integer number (1878058).

Almost surely, 2^21421580 is an apocalyptic number.

21421580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21421580 is an abundant number, since it is smaller than the sum of its proper divisors (23651812).

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

21421580 is a wasteful number, since it uses less digits than its factorization.

21421580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2105 (or 2103 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21421580 is about 4628.3452766621. The cubic root of 21421580 is about 277.7264012834.

Adding to 21421580 its reverse (8512412), we get a palindrome (29933992).

The spelling of 21421580 in words is "twenty-one million, four hundred twenty-one thousand, five hundred eighty".