21012638 has 8 divisors (see below), whose sum is σ = 32252088. Its totient is φ = 10261944.

The previous prime is 21012599. The next prime is 21012647. The reversal of 21012638 is 83621012.

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

It is a congruent number.

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, 122081 + ... + 122252.

It is an arithmetic number, because the mean of its divisors is an integer number (4031511).

Almost surely, 2^21012638 is an apocalyptic number.

21012638 is a deficient number, since it is larger than the sum of its proper divisors (11239450).

21012638 is a wasteful number, since it uses less digits than its factorization.

21012638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244378.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21012638 is about 4583.9544064050. The cubic root of 21012638 is about 275.9477514343.

The spelling of 21012638 in words is "twenty-one million, twelve thousand, six hundred thirty-eight".