20847569 has 2 divisors, whose sum is σ = 20847570. Its totient is φ = 20847568.

The previous prime is 20847551. The next prime is 20847581. The reversal of 20847569 is 96574802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14025025 + 6822544 = 3745^2 + 2612^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20847569 is a prime.

It is a super-2 number, since 2×20847569² = 869242266419522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20847599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10423784 + 10423785.

It is an arithmetic number, because the mean of its divisors is an integer number (10423785).

Almost surely, 2^20847569 is an apocalyptic number.

It is an amenable number.

20847569 is a deficient number, since it is larger than the sum of its proper divisors (1).

20847569 is an equidigital number, since it uses as much as digits as its factorization.

20847569 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120960, while the sum is 41.

The square root of 20847569 is about 4565.9138187224. The cubic root of 20847569 is about 275.2232633190.

The spelling of 20847569 in words is "twenty million, eight hundred forty-seven thousand, five hundred sixty-nine".