209812551655 has 16 divisors (see below), whose sum is σ = 290382776640. Its totient is φ = 142551539712.

The previous prime is 209812551653. The next prime is 209812551661. The reversal of 209812551655 is 556155218902.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 209812551655 - 2¹ = 209812551653 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 209812551599 and 209812551608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209812551653) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27494554 + ... + 27502183.

It is an arithmetic number, because the mean of its divisors is an integer number (18148923540).

Almost surely, 2^209812551655 is an apocalyptic number.

209812551655 is a deficient number, since it is larger than the sum of its proper divisors (80570224985).

209812551655 is a wasteful number, since it uses less digits than its factorization.

209812551655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54996858.

The product of its (nonzero) digits is 1080000, while the sum is 49.

The spelling of 209812551655 in words is "two hundred nine billion, eight hundred twelve million, five hundred fifty-one thousand, six hundred fifty-five".