209890537 has 2 divisors, whose sum is σ = 209890538. Its totient is φ = 209890536.

The previous prime is 209890523. The next prime is 209890543. The reversal of 209890537 is 735098902.

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., 139145616 + 70744921 = 11796^2 + 8411^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209890537 is a prime.

It is equal to p_11595895 and since 209890537 and 11595895 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 209890493 and 209890502.

It is not a weakly prime, because it can be changed into another prime (209890337) 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, 104945268 + 104945269.

It is an arithmetic number, because the mean of its divisors is an integer number (104945269).

Almost surely, 2^209890537 is an apocalyptic number.

It is an amenable number.

209890537 is a deficient number, since it is larger than the sum of its proper divisors (1).

209890537 is an equidigital number, since it uses as much as digits as its factorization.

209890537 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 136080, while the sum is 43.

The square root of 209890537 is about 14487.5994215743. The cubic root of 209890537 is about 594.2889012111.

The spelling of 209890537 in words is "two hundred nine million, eight hundred ninety thousand, five hundred thirty-seven".