155007221 has 4 divisors (see below), whose sum is σ = 155429952. Its totient is φ = 154584492.

The previous prime is 155007179. The next prime is 155007253. The reversal of 155007221 is 122700551.

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 155007221 - 2⁶ = 155007157 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 (155007121) 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, 210815 + ... + 211548.

It is an arithmetic number, because the mean of its divisors is an integer number (38857488).

Almost surely, 2^155007221 is an apocalyptic number.

It is an amenable number.

155007221 is a deficient number, since it is larger than the sum of its proper divisors (422731).

155007221 is an equidigital number, since it uses as much as digits as its factorization.

155007221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422730.

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 155007221 is about 12450.1895969499. The cubic root of 155007221 is about 537.1768770725.

Adding to 155007221 its reverse (122700551), we get a palindrome (277707772).

The spelling of 155007221 in words is "one hundred fifty-five million, seven thousand, two hundred twenty-one".