21447621 has 36 divisors (see below), whose sum is σ = 34257600. Its totient is φ = 12920544.

The previous prime is 21447611. The next prime is 21447683. The reversal of 21447621 is 12674412.

It is not a de Polignac number, because 21447621 - 2⁵ = 21447589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21447611) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 89620 + ... + 89858.

It is an arithmetic number, because the mean of its divisors is an integer number (951600).

Almost surely, 2^21447621 is an apocalyptic number.

It is an amenable number.

21447621 is a deficient number, since it is larger than the sum of its proper divisors (12809979).

21447621 is a wasteful number, since it uses less digits than its factorization.

21447621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330 (or 314 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 21447621 is about 4631.1576306578. The cubic root of 21447621 is about 277.8388944573.

The spelling of 21447621 in words is "twenty-one million, four hundred forty-seven thousand, six hundred twenty-one".