209621051 has 2 divisors, whose sum is σ = 209621052. Its totient is φ = 209621050.

The previous prime is 209621017. The next prime is 209621059. The reversal of 209621051 is 150126902.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209621051 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 209621051.

It is not a weakly prime, because it can be changed into another prime (209621059) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104810525 + 104810526.

It is an arithmetic number, because the mean of its divisors is an integer number (104810526).

Almost surely, 2^209621051 is an apocalyptic number.

209621051 is a deficient number, since it is larger than the sum of its proper divisors (1).

209621051 is an equidigital number, since it uses as much as digits as its factorization.

209621051 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 209621051 is about 14478.2958596653. The cubic root of 209621051 is about 594.0344493241.

Adding to 209621051 its reverse (150126902), we get a palindrome (359747953).

The spelling of 209621051 in words is "two hundred nine million, six hundred twenty-one thousand, fifty-one".