155204321 has 4 divisors (see below), whose sum is σ = 160210944. Its totient is φ = 150197700.

The previous prime is 155204267. The next prime is 155204327. The reversal of 155204321 is 123402551.

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, and also an emirpimes, since its reverse is a distinct semiprime: 123402551 = 881 ⋅140071.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155204321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155204327) 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, 2503265 + ... + 2503326.

It is an arithmetic number, because the mean of its divisors is an integer number (40052736).

Almost surely, 2^155204321 is an apocalyptic number.

It is an amenable number.

155204321 is a deficient number, since it is larger than the sum of its proper divisors (5006623).

155204321 is an equidigital number, since it uses as much as digits as its factorization.

155204321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5006622.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 155204321 is about 12458.1026243967. The cubic root of 155204321 is about 537.4044637125.

Adding to 155204321 its reverse (123402551), we get a palindrome (278606872).

The spelling of 155204321 in words is "one hundred fifty-five million, two hundred four thousand, three hundred twenty-one".