21764406 has 8 divisors (see below), whose sum is σ = 43528824. Its totient is φ = 7254800.

The previous prime is 21764401. The next prime is 21764419. The reversal of 21764406 is 60446712.

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

21764406 is an admirable number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21764401) 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 in 3 ways as a sum of consecutive naturals, for example, 1813695 + ... + 1813706.

It is an arithmetic number, because the mean of its divisors is an integer number (5441103).

Almost surely, 2^21764406 is an apocalyptic number.

21764406 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21764406 is a wasteful number, since it uses less digits than its factorization.

21764406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3627406.

The product of its (nonzero) digits is 8064, while the sum is 30.

The square root of 21764406 is about 4665.2337562013. The cubic root of 21764406 is about 279.2001236306.

The spelling of 21764406 in words is "twenty-one million, seven hundred sixty-four thousand, four hundred six".