21716501 has 4 divisors (see below), whose sum is σ = 21743712. Its totient is φ = 21689292.

The previous prime is 21716489. The next prime is 21716503. The reversal of 21716501 is 10561712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21716501 - 2⁶ = 21716437 is a prime.

It is a Duffinian 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 (21716503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12371 + ... + 14016.

It is an arithmetic number, because the mean of its divisors is an integer number (5435928).

Almost surely, 2^21716501 is an apocalyptic number.

It is an amenable number.

21716501 is a deficient number, since it is larger than the sum of its proper divisors (27211).

21716501 is an equidigital number, since it uses as much as digits as its factorization.

21716501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27210.

The product of its (nonzero) digits is 420, while the sum is 23.

The square root of 21716501 is about 4660.0966728170. The cubic root of 21716501 is about 278.9951267332.

The spelling of 21716501 in words is "twenty-one million, seven hundred sixteen thousand, five hundred one".