155631220 has 12 divisors (see below), whose sum is σ = 326825604. Its totient is φ = 62252480.

The previous prime is 155631199. The next prime is 155631247. The reversal of 155631220 is 22136551.

It can be written as a sum of positive squares in 2 ways, for example, as 92968164 + 62663056 = 9642^2 + 7916^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3890761 + ... + 3890800.

It is an arithmetic number, because the mean of its divisors is an integer number (27235467).

Almost surely, 2^155631220 is an apocalyptic number.

155631220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

155631220 is an abundant number, since it is smaller than the sum of its proper divisors (171194384).

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

155631220 is a wasteful number, since it uses less digits than its factorization.

155631220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7781570 (or 7781568 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 155631220 is about 12475.2242464815. The cubic root of 155631220 is about 537.8967339561.

Adding to 155631220 its reverse (22136551), we get a palindrome (177767771).

The spelling of 155631220 in words is "one hundred fifty-five million, six hundred thirty-one thousand, two hundred twenty".