155551104353221 has 4 divisors (see below), whose sum is σ = 156218705659692. Its totient is φ = 154883503046752.

The previous prime is 155551104353219. The next prime is 155551104353251. The reversal of 155551104353221 is 122353401155551.

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

It can be written as a sum of positive squares in 2 ways, for example, as 59853602453121 + 95697501900100 = 7736511^2 + 9782510^2 .

It is a cyclic number.

It is not a de Polignac number, because 155551104353221 - 2¹ = 155551104353219 is a prime.

It is a super-2 number, since 2×155551104353221² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155551104353251) 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, 333800652886 + ... + 333800653351.

It is an arithmetic number, because the mean of its divisors is an integer number (39054676414923).

Almost surely, 2^{155551104353221} is an apocalyptic number.

It is an amenable number.

155551104353221 is a deficient number, since it is larger than the sum of its proper divisors (667601306471).

155551104353221 is an equidigital number, since it uses as much as digits as its factorization.

155551104353221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 667601306470.

The product of its (nonzero) digits is 450000, while the sum is 43.

The spelling of 155551104353221 in words is "one hundred fifty-five trillion, five hundred fifty-one billion, one hundred four million, three hundred fifty-three thousand, two hundred twenty-one".