21764641 has 8 divisors (see below), whose sum is σ = 23169024. Its totient is φ = 20374080.

The previous prime is 21764627. The next prime is 21764651. The reversal of 21764641 is 14646712.

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

It is a cyclic number.

It is not a de Polignac number, because 21764641 - 2⁷ = 21764513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21764651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 105 + ... + 6598.

It is an arithmetic number, because the mean of its divisors is an integer number (2896128).

Almost surely, 2^21764641 is an apocalyptic number.

It is an amenable number.

21764641 is a deficient number, since it is larger than the sum of its proper divisors (1404383).

21764641 is a wasteful number, since it uses less digits than its factorization.

21764641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6911.

The product of its digits is 8064, while the sum is 31.

The square root of 21764641 is about 4665.2589424382. The cubic root of 21764641 is about 279.2011285097.

The spelling of 21764641 in words is "twenty-one million, seven hundred sixty-four thousand, six hundred forty-one".