209797631 has 4 divisors (see below), whose sum is σ = 210572064. Its totient is φ = 209023200.

The previous prime is 209797603. The next prime is 209797633. The reversal of 209797631 is 136797902.

It is a happy number.

209797631 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 209797631 - 2¹⁰ = 209796607 is a prime.

It is a super-2 number, since 2×209797631² = 88030091946424322, 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 (209797633) 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, 386810 + ... + 387351.

It is an arithmetic number, because the mean of its divisors is an integer number (52643016).

Almost surely, 2^209797631 is an apocalyptic number.

209797631 is a deficient number, since it is larger than the sum of its proper divisors (774433).

209797631 is an equidigital number, since it uses as much as digits as its factorization.

209797631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 774432.

The product of its (nonzero) digits is 142884, while the sum is 44.

The square root of 209797631 is about 14484.3926693528. The cubic root of 209797631 is about 594.2012028741.

The spelling of 209797631 in words is "two hundred nine million, seven hundred ninety-seven thousand, six hundred thirty-one".