20647409 has 2 divisors, whose sum is σ = 20647410. Its totient is φ = 20647408.

The previous prime is 20647387. The next prime is 20647411. The reversal of 20647409 is 90474602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18515809 + 2131600 = 4303^2 + 1460^2 .

It is a cyclic number.

It is not a de Polignac number, because 20647409 - 2¹² = 20643313 is a prime.

It is a super-3 number, since 3×20647409³ (a number of 23 digits) contains 333 as substring.

Together with 20647411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20647489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10323704 + 10323705.

It is an arithmetic number, because the mean of its divisors is an integer number (10323705).

Almost surely, 2^20647409 is an apocalyptic number.

It is an amenable number.

20647409 is a deficient number, since it is larger than the sum of its proper divisors (1).

20647409 is an equidigital number, since it uses as much as digits as its factorization.

20647409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 32.

The square root of 20647409 is about 4543.9420110736. The cubic root of 20647409 is about 274.3396121012.

The spelling of 20647409 in words is "twenty million, six hundred forty-seven thousand, four hundred nine".