121661815 has 32 divisors (see below), whose sum is σ = 166924800. Its totient is φ = 84309120.

The previous prime is 121661791. The next prime is 121661819. The reversal of 121661815 is 518166121.

It is not a de Polignac number, because 121661815 - 2⁹ = 121661303 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121661819) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 131926 + ... + 132844.

It is an arithmetic number, because the mean of its divisors is an integer number (5216400).

Almost surely, 2^121661815 is an apocalyptic number.

121661815 is a deficient number, since it is larger than the sum of its proper divisors (45262985).

121661815 is a wasteful number, since it uses less digits than its factorization.

121661815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1047.

The product of its digits is 2880, while the sum is 31.

The square root of 121661815 is about 11030.0414777099. The cubic root of 121661815 is about 495.5088668968.

The spelling of 121661815 in words is "one hundred twenty-one million, six hundred sixty-one thousand, eight hundred fifteen".