21007738 has 16 divisors (see below), whose sum is σ = 32192640. Its totient is φ = 10279456.

The previous prime is 21007709. The next prime is 21007741. The reversal of 21007738 is 83770012.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18495 + ... + 19597.

It is an arithmetic number, because the mean of its divisors is an integer number (2012040).

Almost surely, 2^21007738 is an apocalyptic number.

21007738 is a deficient number, since it is larger than the sum of its proper divisors (11184902).

21007738 is a wasteful number, since it uses less digits than its factorization.

21007738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1301.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21007738 is about 4583.4199022128. The cubic root of 21007738 is about 275.9263000725.

The spelling of 21007738 in words is "twenty-one million, seven thousand, seven hundred thirty-eight".