21489697 has 2 divisors, whose sum is σ = 21489698. Its totient is φ = 21489696.

The previous prime is 21489661. The next prime is 21489701. The reversal of 21489697 is 79698412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15492096 + 5997601 = 3936^2 + 2449^2 .

It is a cyclic number.

It is not a de Polignac number, because 21489697 - 2¹⁹ = 20965409 is a prime.

It is not a weakly prime, because it can be changed into another prime (21489607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10744848 + 10744849.

It is an arithmetic number, because the mean of its divisors is an integer number (10744849).

Almost surely, 2^21489697 is an apocalyptic number.

It is an amenable number.

21489697 is a deficient number, since it is larger than the sum of its proper divisors (1).

21489697 is an equidigital number, since it uses as much as digits as its factorization.

21489697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 46.

The square root of 21489697 is about 4635.6981135531. The cubic root of 21489697 is about 278.0204641354.

The spelling of 21489697 in words is "twenty-one million, four hundred eighty-nine thousand, six hundred ninety-seven".