155520121 has 4 divisors (see below), whose sum is σ = 159136912. Its totient is φ = 151903332.

The previous prime is 155520119. The next prime is 155520137. The reversal of 155520121 is 121025551.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 155520121 - 2¹ = 155520119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 155520092 and 155520101.

It is not an unprimeable number, because it can be changed into a prime (155520161) 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, 1808331 + ... + 1808416.

It is an arithmetic number, because the mean of its divisors is an integer number (39784228).

Almost surely, 2^155520121 is an apocalyptic number.

It is an amenable number.

155520121 is a deficient number, since it is larger than the sum of its proper divisors (3616791).

155520121 is an equidigital number, since it uses as much as digits as its factorization.

155520121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3616790.

The product of its (nonzero) digits is 500, while the sum is 22.

The square root of 155520121 is about 12470.7706658410. The cubic root of 155520121 is about 537.7687090544.

Adding to 155520121 its reverse (121025551), we get a palindrome (276545672).

The spelling of 155520121 in words is "one hundred fifty-five million, five hundred twenty thousand, one hundred twenty-one".