155245221 has 16 divisors (see below), whose sum is σ = 230390400. Its totient is φ = 103317984.

The previous prime is 155245213. The next prime is 155245253. The reversal of 155245221 is 122542551.

It is not a de Polignac number, because 155245221 - 2³ = 155245213 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155245201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12000 + ... + 21318.

It is an arithmetic number, because the mean of its divisors is an integer number (14399400).

Almost surely, 2^155245221 is an apocalyptic number.

It is an amenable number.

155245221 is a deficient number, since it is larger than the sum of its proper divisors (75145179).

155245221 is an equidigital number, since it uses as much as digits as its factorization.

155245221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9945 (or 9939 counting only the distinct ones).

The product of its digits is 4000, while the sum is 27.

The square root of 155245221 is about 12459.7440182373. The cubic root of 155245221 is about 537.4516658178.

Adding to 155245221 its reverse (122542551), we get a palindrome (277787772).

The spelling of 155245221 in words is "one hundred fifty-five million, two hundred forty-five thousand, two hundred twenty-one".