209718972126 has 32 divisors (see below), whose sum is σ = 482112583200. Its totient is φ = 67495760640.

The previous prime is 209718972109. The next prime is 209718972181. The reversal of 209718972126 is 621279817902.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66958515 + ... + 66961646.

It is an arithmetic number, because the mean of its divisors is an integer number (15066018225).

Almost surely, 2^209718972126 is an apocalyptic number.

209718972126 is an abundant number, since it is smaller than the sum of its proper divisors (272393611074).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

209718972126 is a wasteful number, since it uses less digits than its factorization.

209718972126 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133920201 (or 133920195 counting only the distinct ones).

The product of its (nonzero) digits is 1524096, while the sum is 54.

The spelling of 209718972126 in words is "two hundred nine billion, seven hundred eighteen million, nine hundred seventy-two thousand, one hundred twenty-six".