21364657 has 2 divisors, whose sum is σ = 21364658. Its totient is φ = 21364656.

The previous prime is 21364643. The next prime is 21364661. The reversal of 21364657 is 75646312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12418576 + 8946081 = 3524^2 + 2991^2 .

It is a cyclic number.

It is not a de Polignac number, because 21364657 - 2¹¹ = 21362609 is a prime.

It is not a weakly prime, because it can be changed into another prime (21364627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682328 + 10682329.

It is an arithmetic number, because the mean of its divisors is an integer number (10682329).

Almost surely, 2^21364657 is an apocalyptic number.

It is an amenable number.

21364657 is a deficient number, since it is larger than the sum of its proper divisors (1).

21364657 is an equidigital number, since it uses as much as digits as its factorization.

21364657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 34.

The square root of 21364657 is about 4622.1917961071. The cubic root of 21364657 is about 277.4801847172.

The spelling of 21364657 in words is "twenty-one million, three hundred sixty-four thousand, six hundred fifty-seven".