21906242 has 8 divisors (see below), whose sum is σ = 32959632. Its totient is φ = 10919700.

The previous prime is 21906233. The next prime is 21906263. The reversal of 21906242 is 24260912.

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

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, 15884 + ... + 17207.

It is an arithmetic number, because the mean of its divisors is an integer number (4119954).

Almost surely, 2^21906242 is an apocalyptic number.

21906242 is a deficient number, since it is larger than the sum of its proper divisors (11053390).

21906242 is a wasteful number, since it uses less digits than its factorization.

21906242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33424.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21906242 is about 4680.4104520864. The cubic root of 21906242 is about 279.8053153470.

The spelling of 21906242 in words is "twenty-one million, nine hundred six thousand, two hundred forty-two".