21216548 has 6 divisors (see below), whose sum is σ = 37128966. Its totient is φ = 10608272.

The previous prime is 21216539. The next prime is 21216551. The reversal of 21216548 is 84561212.

It can be written as a sum of positive squares in only one way, i.e., 10705984 + 10510564 = 3272^2 + 3242^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21216548.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2652065 + ... + 2652072.

It is an arithmetic number, because the mean of its divisors is an integer number (6188161).

Almost surely, 2^21216548 is an apocalyptic number.

It is an amenable number.

21216548 is a deficient number, since it is larger than the sum of its proper divisors (15912418).

21216548 is a wasteful number, since it uses less digits than its factorization.

21216548 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5304141 (or 5304139 counting only the distinct ones).

The product of its digits is 3840, while the sum is 29.

The square root of 21216548 is about 4606.1424207247. The cubic root of 21216548 is about 276.8374932506.

The spelling of 21216548 in words is "twenty-one million, two hundred sixteen thousand, five hundred forty-eight".