21182638 has 4 divisors (see below), whose sum is σ = 31773960. Its totient is φ = 10591318.

The previous prime is 21182591. The next prime is 21182647. The reversal of 21182638 is 83628112.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5295658 + ... + 5295661.

It is an arithmetic number, because the mean of its divisors is an integer number (7943490).

Almost surely, 2^21182638 is an apocalyptic number.

21182638 is a deficient number, since it is larger than the sum of its proper divisors (10591322).

21182638 is a wasteful number, since it uses less digits than its factorization.

21182638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10591321.

The product of its digits is 4608, while the sum is 31.

The square root of 21182638 is about 4602.4599943943. The cubic root of 21182638 is about 276.6899265940.

The spelling of 21182638 in words is "twenty-one million, one hundred eighty-two thousand, six hundred thirty-eight".