121651 has 4 divisors (see below), whose sum is σ = 122400. Its totient is φ = 120904.

The previous prime is 121637. The next prime is 121661. The reversal of 121651 is 156121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 156121 = 7 ⋅22303.

It is a cyclic number.

It is not a de Polignac number, because 121651 - 2⁷ = 121523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16 + ... + 493.

It is an arithmetic number, because the mean of its divisors is an integer number (30600).

2¹²¹⁶⁵¹ is an apocalyptic number.

121651 is a deficient number, since it is larger than the sum of its proper divisors (749).

121651 is an equidigital number, since it uses as much as digits as its factorization.

121651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 748.

The product of its digits is 60, while the sum is 16.

The square root of 121651 is about 348.7850340826. The cubic root of 121651 is about 49.5494183881.

Adding to 121651 its reverse (156121), we get a palindrome (277772).

The spelling of 121651 in words is "one hundred twenty-one thousand, six hundred fifty-one".