21307438 has 4 divisors (see below), whose sum is σ = 31961160. Its totient is φ = 10653718.

The previous prime is 21307423. The next prime is 21307441. The reversal of 21307438 is 83470312.

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

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, 5326858 + ... + 5326861.

It is an arithmetic number, because the mean of its divisors is an integer number (7990290).

Almost surely, 2^21307438 is an apocalyptic number.

21307438 is a deficient number, since it is larger than the sum of its proper divisors (10653722).

21307438 is a wasteful number, since it uses less digits than its factorization.

21307438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10653721.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21307438 is about 4615.9980502596. The cubic root of 21307438 is about 277.2322466715.

The spelling of 21307438 in words is "twenty-one million, three hundred seven thousand, four hundred thirty-eight".