21716489 has 2 divisors, whose sum is σ = 21716490. Its totient is φ = 21716488.

The previous prime is 21716479. The next prime is 21716503. The reversal of 21716489 is 98461712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20070400 + 1646089 = 4480^2 + 1283^2 .

It is a cyclic number.

It is not a de Polignac number, because 21716489 - 2¹² = 21712393 is a prime.

It is not a weakly prime, because it can be changed into another prime (21716479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858244 + 10858245.

It is an arithmetic number, because the mean of its divisors is an integer number (10858245).

Almost surely, 2^21716489 is an apocalyptic number.

It is an amenable number.

21716489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21716489 is an equidigital number, since it uses as much as digits as its factorization.

21716489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 38.

The square root of 21716489 is about 4660.0953852899. The cubic root of 21716489 is about 278.9950753446.

The spelling of 21716489 in words is "twenty-one million, seven hundred sixteen thousand, four hundred eighty-nine".