155631213 has 20 divisors (see below), whose sum is σ = 238774140. Its totient is φ = 100948032.

The previous prime is 155631199. The next prime is 155631247. The reversal of 155631213 is 312136551.

155631213 is a `hidden beast` number, since 1 + 5 + 5 + 631 + 21 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 145878084 + 9753129 = 12078^2 + 3123^2 .

It is not a de Polignac number, because 155631213 - 2⁶ = 155631149 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 (155631263) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 22968 + ... + 28961.

It is an arithmetic number, because the mean of its divisors is an integer number (11938707).

Almost surely, 2^155631213 is an apocalyptic number.

It is an amenable number.

155631213 is a deficient number, since it is larger than the sum of its proper divisors (83142927).

155631213 is an equidigital number, since it uses as much as digits as its factorization.

155631213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51978 (or 51969 counting only the distinct ones).

The product of its digits is 2700, while the sum is 27.

The square root of 155631213 is about 12475.2239659254. The cubic root of 155631213 is about 537.8967258916.

Adding to 155631213 its reverse (312136551), we get a palindrome (467767764).

The spelling of 155631213 in words is "one hundred fifty-five million, six hundred thirty-one thousand, two hundred thirteen".