20864609 has 2 divisors, whose sum is σ = 20864610. Its totient is φ = 20864608.

The previous prime is 20864587. The next prime is 20864617. The reversal of 20864609 is 90646802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20611600 + 253009 = 4540^2 + 503^2 .

It is a cyclic number.

It is not a de Polignac number, because 20864609 - 2¹⁶ = 20799073 is a prime.

It is not a weakly prime, because it can be changed into another prime (20864009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10432304 + 10432305.

It is an arithmetic number, because the mean of its divisors is an integer number (10432305).

Almost surely, 2^20864609 is an apocalyptic number.

It is an amenable number.

20864609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20864609 is an equidigital number, since it uses as much as digits as its factorization.

20864609 is an evil number, because the sum of its binary digits is even.

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

The square root of 20864609 is about 4567.7794386332. The cubic root of 20864609 is about 275.2982285301.

The spelling of 20864609 in words is "twenty million, eight hundred sixty-four thousand, six hundred nine".