21305942 has 8 divisors (see below), whose sum is σ = 36524496. Its totient is φ = 9131112.

The previous prime is 21305939. The next prime is 21305983. The reversal of 21305942 is 24950312.

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

It is a congruent 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 3 ways as a sum of consecutive naturals, for example, 760913 + ... + 760940.

It is an arithmetic number, because the mean of its divisors is an integer number (4565562).

Almost surely, 2^21305942 is an apocalyptic number.

21305942 is a deficient number, since it is larger than the sum of its proper divisors (15218554).

21305942 is a wasteful number, since it uses less digits than its factorization.

21305942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521862.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 21305942 is about 4615.8360022860. The cubic root of 21305942 is about 277.2257583402.

The spelling of 21305942 in words is "twenty-one million, three hundred five thousand, nine hundred forty-two".