21730649 has 2 divisors, whose sum is σ = 21730650. Its totient is φ = 21730648.

The previous prime is 21730637. The next prime is 21730663. The reversal of 21730649 is 94603712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19642624 + 2088025 = 4432^2 + 1445^2 .

It is a cyclic number.

It is not a de Polignac number, because 21730649 - 2⁸ = 21730393 is a prime.

It is a super-2 number, since 2×21730649² = 944442211922402, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21730249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865324 + 10865325.

It is an arithmetic number, because the mean of its divisors is an integer number (10865325).

Almost surely, 2^21730649 is an apocalyptic number.

It is an amenable number.

21730649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21730649 is an equidigital number, since it uses as much as digits as its factorization.

21730649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 21730649 is about 4661.6144199193. The cubic root of 21730649 is about 279.0557007360.

The spelling of 21730649 in words is "twenty-one million, seven hundred thirty thousand, six hundred forty-nine".