155221540 has 12 divisors (see below), whose sum is σ = 325965276. Its totient is φ = 62088608.

The previous prime is 155221523. The next prime is 155221553. The reversal of 155221540 is 45122551.

155221540 is digitally balanced in base 3 and base 9, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 105349696 + 49871844 = 10264^2 + 7062^2 .

155221540 is strictly pandigital in base 9.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3880519 + ... + 3880558.

It is an arithmetic number, because the mean of its divisors is an integer number (27163773).

Almost surely, 2^155221540 is an apocalyptic number.

155221540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

155221540 is an abundant number, since it is smaller than the sum of its proper divisors (170743736).

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

155221540 is a wasteful number, since it uses less digits than its factorization.

155221540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7761086 (or 7761084 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

The square root of 155221540 is about 12458.7936815729. The cubic root of 155221540 is about 537.4243369248.

The spelling of 155221540 in words is "one hundred fifty-five million, two hundred twenty-one thousand, five hundred forty".