21489623 has 2 divisors, whose sum is σ = 21489624. Its totient is φ = 21489622.

The previous prime is 21489619. The next prime is 21489631. The reversal of 21489623 is 32698412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21489623 - 2² = 21489619 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21489653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10744811 + 10744812.

It is an arithmetic number, because the mean of its divisors is an integer number (10744812).

Almost surely, 2^21489623 is an apocalyptic number.

21489623 is a deficient number, since it is larger than the sum of its proper divisors (1).

21489623 is an equidigital number, since it uses as much as digits as its factorization.

21489623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 35.

The square root of 21489623 is about 4635.6901320084. The cubic root of 21489623 is about 278.0201450129.

The spelling of 21489623 in words is "twenty-one million, four hundred eighty-nine thousand, six hundred twenty-three".