155221000 has 128 divisors (see below), whose sum is σ = 403004160. Its totient is φ = 55488000.

The previous prime is 155220991. The next prime is 155221007. The reversal of 155221000 is 122551.

It is not an unprimeable number, because it can be changed into a prime (155221007) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1132932 + ... + 1133068.

It is an arithmetic number, because the mean of its divisors is an integer number (3148470).

Almost surely, 2^155221000 is an apocalyptic number.

155221000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 155221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (201502080).

155221000 is an abundant number, since it is smaller than the sum of its proper divisors (247783160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

155221000 is a wasteful number, since it uses less digits than its factorization.

155221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272 (or 258 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 155221000 is about 12458.7720101140. The cubic root of 155221000 is about 537.4237137091.

Adding to 155221000 its reverse (122551), we get a palindrome (155343551).

The spelling of 155221000 in words is "one hundred fifty-five million, two hundred twenty-one thousand".