209467981 has 4 divisors (see below), whose sum is σ = 210564864. Its totient is φ = 208371100.

The previous prime is 209467967. The next prime is 209467991. The reversal of 209467981 is 189764902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 209467981 - 2⁹ = 209467469 is a prime.

It is a super-4 number, since 4×209467981⁴ (a number of 34 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209467901) 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, 548155 + ... + 548536.

It is an arithmetic number, because the mean of its divisors is an integer number (52641216).

Almost surely, 2^209467981 is an apocalyptic number.

It is an amenable number.

209467981 is a deficient number, since it is larger than the sum of its proper divisors (1096883).

209467981 is a wasteful number, since it uses less digits than its factorization.

209467981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1096882.

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 209467981 is about 14473.0087058635. The cubic root of 209467981 is about 593.8898216822.

The spelling of 209467981 in words is "two hundred nine million, four hundred sixty-seven thousand, nine hundred eighty-one".