21906338 has 4 divisors (see below), whose sum is σ = 32859510. Its totient is φ = 10953168.

The previous prime is 21906337. The next prime is 21906359. The reversal of 21906338 is 83360912.

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

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 994009 = 4573^2 + 997^2 .

It is not an unprimeable number, because it can be changed into a prime (21906337) by changing a digit.

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 as a sum of consecutive naturals, namely, 5476583 + ... + 5476586.

Almost surely, 2^21906338 is an apocalyptic number.

21906338 is a deficient number, since it is larger than the sum of its proper divisors (10953172).

21906338 is a wasteful number, since it uses less digits than its factorization.

21906338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10953171.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 21906338 is about 4680.4207075860. The cubic root of 21906338 is about 279.8057240778.

The spelling of 21906338 in words is "twenty-one million, nine hundred six thousand, three hundred thirty-eight".