20217949 has 2 divisors, whose sum is σ = 20217950. Its totient is φ = 20217948.

The previous prime is 20217941. The next prime is 20218013. The reversal of 20217949 is 94971202.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15155449 + 5062500 = 3893^2 + 2250^2 .

It is a cyclic number.

It is not a de Polignac number, because 20217949 - 2³ = 20217941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20217941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10108974 + 10108975.

It is an arithmetic number, because the mean of its divisors is an integer number (10108975).

Almost surely, 2^20217949 is an apocalyptic number.

It is an amenable number.

20217949 is a deficient number, since it is larger than the sum of its proper divisors (1).

20217949 is an equidigital number, since it uses as much as digits as its factorization.

20217949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 20217949 is about 4496.4373675166. The cubic root of 20217949 is about 272.4242092058.

The spelling of 20217949 in words is "twenty million, two hundred seventeen thousand, nine hundred forty-nine".