121521661 has 8 divisors (see below), whose sum is σ = 128831040. Its totient is φ = 114230208.

The previous prime is 121521641. The next prime is 121521667. The reversal of 121521661 is 166125121.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-121521661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121521667) 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, 11050 + ... + 19108.

It is an arithmetic number, because the mean of its divisors is an integer number (16103880).

Almost surely, 2^121521661 is an apocalyptic number.

It is an amenable number.

121521661 is a deficient number, since it is larger than the sum of its proper divisors (7309379).

121521661 is an equidigital number, since it uses as much as digits as its factorization.

121521661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8963.

The product of its digits is 720, while the sum is 25.

The square root of 121521661 is about 11023.6863616487. The cubic root of 121521661 is about 495.3185189376.

Adding to 121521661 its reverse (166125121), we get a palindrome (287646782).

The spelling of 121521661 in words is "one hundred twenty-one million, five hundred twenty-one thousand, six hundred sixty-one".