20212909 has 2 divisors, whose sum is σ = 20212910. Its totient is φ = 20212908.

The previous prime is 20212891. The next prime is 20212931. The reversal of 20212909 is 90921202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16990884 + 3222025 = 4122^2 + 1795^2 .

It is a cyclic number.

It is not a de Polignac number, because 20212909 - 2¹⁵ = 20180141 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20282909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10106454 + 10106455.

It is an arithmetic number, because the mean of its divisors is an integer number (10106455).

Almost surely, 2^20212909 is an apocalyptic number.

It is an amenable number.

20212909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20212909 is an equidigital number, since it uses as much as digits as its factorization.

20212909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 20212909 is about 4495.8768888839. The cubic root of 20212909 is about 272.4015703760.

The spelling of 20212909 in words is "twenty million, two hundred twelve thousand, nine hundred nine".