209706431 has 18 divisors (see below), whose sum is σ = 236492088. Its totient is φ = 185812000.

The previous prime is 209706421. The next prime is 209706457. The reversal of 209706431 is 134607902.

It is a de Polignac number, because none of the positive numbers 2^k-209706431 is a prime.

It is a super-2 number, since 2×209706431² = 87953574405515522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209706421) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 202886 + ... + 203916.

Almost surely, 2^209706431 is an apocalyptic number.

209706431 is a deficient number, since it is larger than the sum of its proper divisors (26785657).

209706431 is a wasteful number, since it uses less digits than its factorization.

209706431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1135 (or 1083 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 209706431 is about 14481.2441109181. The cubic root of 209706431 is about 594.1150897251.

The spelling of 209706431 in words is "two hundred nine million, seven hundred six thousand, four hundred thirty-one".