21723073 has 2 divisors, whose sum is σ = 21723074. Its totient is φ = 21723072.

The previous prime is 21723067. The next prime is 21723101. The reversal of 21723073 is 37032712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12794929 + 8928144 = 3577^2 + 2988^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21723073 is a prime.

It is not a weakly prime, because it can be changed into another prime (21723043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861536 + 10861537.

It is an arithmetic number, because the mean of its divisors is an integer number (10861537).

Almost surely, 2^21723073 is an apocalyptic number.

It is an amenable number.

21723073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21723073 is an equidigital number, since it uses as much as digits as its factorization.

21723073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 25.

The square root of 21723073 is about 4660.8017550632. The cubic root of 21723073 is about 279.0232677160.

Adding to 21723073 its reverse (37032712), we get a palindrome (58755785).

The spelling of 21723073 in words is "twenty-one million, seven hundred twenty-three thousand, seventy-three".