121561311616 has 16 divisors (see below), whose sum is σ = 242172925740. Its totient is φ = 60780655744.

The previous prime is 121561311587. The next prime is 121561311617. The reversal of 121561311616 is 616113165121.

It is a tau number, because it is divible by the number of its divisors (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121561311617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 474848746 + ... + 474849001.

Almost surely, 2^121561311616 is an apocalyptic number.

121561311616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

121561311616 is a deficient number, since it is larger than the sum of its proper divisors (120611614124).

121561311616 is an frugal number, since it uses more digits than its factorization.

121561311616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 949697761 (or 949697749 counting only the distinct ones).

The product of its digits is 6480, while the sum is 34.

Adding to 121561311616 its reverse (616113165121), we get a palindrome (737674476737).

The spelling of 121561311616 in words is "one hundred twenty-one billion, five hundred sixty-one million, three hundred eleven thousand, six hundred sixteen".