21420766 has 8 divisors (see below), whose sum is σ = 32336280. Its totient is φ = 10642008.

The previous prime is 21420761. The next prime is 21420793. The reversal of 21420766 is 66702412.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33796 + ... + 34423.

It is an arithmetic number, because the mean of its divisors is an integer number (4042035).

Almost surely, 2^21420766 is an apocalyptic number.

21420766 is a deficient number, since it is larger than the sum of its proper divisors (10915514).

21420766 is a wasteful number, since it uses less digits than its factorization.

21420766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68378.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21420766 is about 4628.2573394313. The cubic root of 21420766 is about 277.7228834577.

The spelling of 21420766 in words is "twenty-one million, four hundred twenty thousand, seven hundred sixty-six".