1211727617661 has 8 divisors (see below), whose sum is σ = 1762512898464. Its totient is φ = 734380374320.

The previous prime is 1211727617599. The next prime is 1211727617663. The reversal of 1211727617661 is 1667167271121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1211727617661 - 2¹⁷ = 1211727486589 is a prime.

It is a super-2 number, since 2×1211727617661² (a number of 25 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1211727617661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211727617663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18359509326 + ... + 18359509391.

It is an arithmetic number, because the mean of its divisors is an integer number (220314112308).

Almost surely, 2^{1211727617661} is an apocalyptic number.

1211727617661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1211727617661 is a deficient number, since it is larger than the sum of its proper divisors (550785280803).

1211727617661 is a wasteful number, since it uses less digits than its factorization.

1211727617661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36719018731.

The product of its digits is 296352, while the sum is 48.

The spelling of 1211727617661 in words is "one trillion, two hundred eleven billion, seven hundred twenty-seven million, six hundred seventeen thousand, six hundred sixty-one".