21716289 has 16 divisors (see below), whose sum is σ = 36768640. Its totient is φ = 12409200.

The previous prime is 21716287. The next prime is 21716291. The reversal of 21716289 is 98261712.

21716289 is a `hidden beast` number, since 21 + 7 + 1 + 628 + 9 = 666.

It is an interprime number because it is at equal distance from previous prime (21716287) and next prime (21716291).

It is not a de Polignac number, because 21716289 - 2¹ = 21716287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21716287) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57262 + ... + 57639.

It is an arithmetic number, because the mean of its divisors is an integer number (2298040).

Almost surely, 2^21716289 is an apocalyptic number.

It is an amenable number.

21716289 is a deficient number, since it is larger than the sum of its proper divisors (15052351).

21716289 is a wasteful number, since it uses less digits than its factorization.

21716289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114917 (or 114911 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21716289 is about 4660.0739264522. The cubic root of 21716289 is about 278.9942188651.

The spelling of 21716289 in words is "twenty-one million, seven hundred sixteen thousand, two hundred eighty-nine".