20557447 has 2 divisors, whose sum is σ = 20557448. Its totient is φ = 20557446.

The previous prime is 20557421. The next prime is 20557451. The reversal of 20557447 is 74475502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20557447 - 2⁷ = 20557319 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20557477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10278723 + 10278724.

It is an arithmetic number, because the mean of its divisors is an integer number (10278724).

Almost surely, 2^20557447 is an apocalyptic number.

20557447 is a deficient number, since it is larger than the sum of its proper divisors (1).

20557447 is an equidigital number, since it uses as much as digits as its factorization.

20557447 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39200, while the sum is 34.

The square root of 20557447 is about 4534.0320907554. The cubic root of 20557447 is about 273.9405939728.

The spelling of 20557447 in words is "twenty million, five hundred fifty-seven thousand, four hundred forty-seven".