20905901 has 2 divisors, whose sum is σ = 20905902. Its totient is φ = 20905900.

The previous prime is 20905877. The next prime is 20905921. The reversal of 20905901 is 10950902.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20702500 + 203401 = 4550^2 + 451^2 .

It is a cyclic number.

It is not a de Polignac number, because 20905901 - 2¹⁸ = 20643757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20905921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10452950 + 10452951.

It is an arithmetic number, because the mean of its divisors is an integer number (10452951).

Almost surely, 2^20905901 is an apocalyptic number.

It is an amenable number.

20905901 is a deficient number, since it is larger than the sum of its proper divisors (1).

20905901 is an equidigital number, since it uses as much as digits as its factorization.

20905901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 810, while the sum is 26.

The square root of 20905901 is about 4572.2971250784. The cubic root of 20905901 is about 275.4797180511.

The spelling of 20905901 in words is "twenty million, nine hundred five thousand, nine hundred one".