21055538 has 8 divisors (see below), whose sum is σ = 36095232. Its totient is φ = 9023796.

The previous prime is 21055513. The next prime is 21055543. The reversal of 21055538 is 83555012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21055538.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 751970 + ... + 751997.

It is an arithmetic number, because the mean of its divisors is an integer number (4511904).

Almost surely, 2^21055538 is an apocalyptic number.

21055538 is a deficient number, since it is larger than the sum of its proper divisors (15039694).

21055538 is a wasteful number, since it uses less digits than its factorization.

21055538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1503976.

The product of its (nonzero) digits is 6000, while the sum is 29.

The square root of 21055538 is about 4588.6313863722. The cubic root of 21055538 is about 276.1354180390.

The spelling of 21055538 in words is "twenty-one million, fifty-five thousand, five hundred thirty-eight".