21197489 has 2 divisors, whose sum is σ = 21197490. Its totient is φ = 21197488.

The previous prime is 21197479. The next prime is 21197551. The reversal of 21197489 is 98479112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21003889 + 193600 = 4583^2 + 440^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21197489 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21197479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10598744 + 10598745.

It is an arithmetic number, because the mean of its divisors is an integer number (10598745).

Almost surely, 2^21197489 is an apocalyptic number.

It is an amenable number.

21197489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21197489 is an equidigital number, since it uses as much as digits as its factorization.

21197489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 41.

The square root of 21197489 is about 4604.0730880385. The cubic root of 21197489 is about 276.7545732822.

The spelling of 21197489 in words is "twenty-one million, one hundred ninety-seven thousand, four hundred eighty-nine".