121533551 has 4 divisors (see below), whose sum is σ = 121854600. Its totient is φ = 121212504.

The previous prime is 121533487. The next prime is 121533613. The reversal of 121533551 is 155335121.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 121533551 - 2⁶ = 121533487 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 121533551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121533851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 159956 + ... + 160713.

It is an arithmetic number, because the mean of its divisors is an integer number (30463650).

Almost surely, 2^121533551 is an apocalyptic number.

121533551 is a deficient number, since it is larger than the sum of its proper divisors (321049).

121533551 is an equidigital number, since it uses as much as digits as its factorization.

121533551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321048.

The product of its digits is 2250, while the sum is 26.

The square root of 121533551 is about 11024.2256417401. The cubic root of 121533551 is about 495.3346728344.

Adding to 121533551 its reverse (155335121), we get a palindrome (276868672).

The spelling of 121533551 in words is "one hundred twenty-one million, five hundred thirty-three thousand, five hundred fifty-one".