21207388 has 12 divisors (see below), whose sum is σ = 37442160. Its totient is φ = 10509632.

The previous prime is 21207377. The next prime is 21207421. The reversal of 21207388 is 88370212.

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, 23008 + ... + 23911.

It is an arithmetic number, because the mean of its divisors is an integer number (3120180).

Almost surely, 2^21207388 is an apocalyptic number.

It is an amenable number.

21207388 is a deficient number, since it is larger than the sum of its proper divisors (16234772).

21207388 is a wasteful number, since it uses less digits than its factorization.

21207388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47036 (or 47034 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 21207388 is about 4605.1479889359. The cubic root of 21207388 is about 276.7976470503.

The spelling of 21207388 in words is "twenty-one million, two hundred seven thousand, three hundred eighty-eight".