209149481 has 2 divisors, whose sum is σ = 209149482. Its totient is φ = 209149480.

The previous prime is 209149471. The next prime is 209149489. The reversal of 209149481 is 184941902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155625625 + 53523856 = 12475^2 + 7316^2 .

It is a cyclic number.

It is not a de Polignac number, because 209149481 - 2¹⁴ = 209133097 is a prime.

It is a super-2 number, since 2×209149481² = 87487010805138722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209149489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104574740 + 104574741.

It is an arithmetic number, because the mean of its divisors is an integer number (104574741).

Almost surely, 2^209149481 is an apocalyptic number.

It is an amenable number.

209149481 is a deficient number, since it is larger than the sum of its proper divisors (1).

209149481 is an equidigital number, since it uses as much as digits as its factorization.

209149481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 209149481 is about 14462.0012792144. The cubic root of 209149481 is about 593.5886621143.

The spelling of 209149481 in words is "two hundred nine million, one hundred forty-nine thousand, four hundred eighty-one".