21602689 has 2 divisors, whose sum is σ = 21602690. Its totient is φ = 21602688.

The previous prime is 21602687. The next prime is 21602719. The reversal of 21602689 is 98620612.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16000000 + 5602689 = 4000^2 + 2367^2 .

It is a cyclic number.

It is not a de Polignac number, because 21602689 - 2¹ = 21602687 is a prime.

Together with 21602687, it forms a pair of twin primes.

It is equal to p_1365658 and since 21602689 and 1365658 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21602687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10801344 + 10801345.

It is an arithmetic number, because the mean of its divisors is an integer number (10801345).

Almost surely, 2^21602689 is an apocalyptic number.

It is an amenable number.

21602689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21602689 is an equidigital number, since it uses as much as digits as its factorization.

21602689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 21602689 is about 4647.8692967854. The cubic root of 21602689 is about 278.5068862339.

The spelling of 21602689 in words is "twenty-one million, six hundred two thousand, six hundred eighty-nine".