155221920 has 480 divisors, whose sum is σ = 658627200. Its totient is φ = 33675264.

The previous prime is 155221889. The next prime is 155221921. The reversal of 155221920 is 29122551.

155221920 is a `hidden beast` number, since 1 + 552 + 21 + 92 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

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 (155221921) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 2630851 + ... + 2630909.

It is an arithmetic number, because the mean of its divisors is an integer number (1372140).

Almost surely, 2^155221920 is an apocalyptic number.

155221920 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 155221920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (329313600).

155221920 is an abundant number, since it is smaller than the sum of its proper divisors (503405280).

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

155221920 is a wasteful number, since it uses less digits than its factorization.

155221920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122 (or 105 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 155221920 is about 12458.8089318361. The cubic root of 155221920 is about 537.4247754831.

The spelling of 155221920 in words is "one hundred fifty-five million, two hundred twenty-one thousand, nine hundred twenty".