121721216 has 16 divisors (see below), whose sum is σ = 242491740. Its totient is φ = 60860544.

The previous prime is 121721209. The next prime is 121721219. The reversal of 121721216 is 612127121.

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

It is a junction number, because it is equal to n+sod(n) for n = 121721191 and 121721200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121721219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 475346 + ... + 475601.

Almost surely, 2^121721216 is an apocalyptic number.

121721216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

121721216 is a deficient number, since it is larger than the sum of its proper divisors (120770524).

121721216 is an frugal number, since it uses more digits than its factorization.

121721216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 950961 (or 950949 counting only the distinct ones).

The product of its digits is 336, while the sum is 23.

The square root of 121721216 is about 11032.7338407124. The cubic root of 121721216 is about 495.5894973263.

Adding to 121721216 its reverse (612127121), we get a palindrome (733848337).

The spelling of 121721216 in words is "one hundred twenty-one million, seven hundred twenty-one thousand, two hundred sixteen".