209929960421 has 4 divisors (see below), whose sum is σ = 213371435244. Its totient is φ = 206488485600.

The previous prime is 209929960399. The next prime is 209929960477. The reversal of 209929960421 is 124069929902.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32279512225 + 177650448196 = 179665^2 + 421486^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209929960421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209929960921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1720737320 + ... + 1720737441.

It is an arithmetic number, because the mean of its divisors is an integer number (53342858811).

Almost surely, 2^209929960421 is an apocalyptic number.

It is an amenable number.

209929960421 is a deficient number, since it is larger than the sum of its proper divisors (3441474823).

209929960421 is an equidigital number, since it uses as much as digits as its factorization.

209929960421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3441474822.

The product of its (nonzero) digits is 1259712, while the sum is 53.

The spelling of 209929960421 in words is "two hundred nine billion, nine hundred twenty-nine million, nine hundred sixty thousand, four hundred twenty-one".