155641628221 has 4 divisors (see below), whose sum is σ = 155648923612. Its totient is φ = 155634332832.

The previous prime is 155641628203. The next prime is 155641628231. The reversal of 155641628221 is 122826146551.

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 140989736196 + 14651892025 = 375486^2 + 121045^2 .

It is a cyclic number.

It is not a de Polignac number, because 155641628221 - 2⁹ = 155641627709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155641628201) 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, 3615600 + ... + 3658393.

It is an arithmetic number, because the mean of its divisors is an integer number (38912230903).

Almost surely, 2^155641628221 is an apocalyptic number.

It is an amenable number.

155641628221 is a deficient number, since it is larger than the sum of its proper divisors (7295391).

155641628221 is an equidigital number, since it uses as much as digits as its factorization.

155641628221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7295390.

The product of its digits is 230400, while the sum is 43.

The spelling of 155641628221 in words is "one hundred fifty-five billion, six hundred forty-one million, six hundred twenty-eight thousand, two hundred twenty-one".