155312231 has 4 divisors (see below), whose sum is σ = 157630392. Its totient is φ = 152994072.

The previous prime is 155312219. The next prime is 155312233. The reversal of 155312231 is 132213551.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 132213551 = 2347 ⋅56333.

It is a cyclic number.

It is not a de Polignac number, because 155312231 - 2⁶ = 155312167 is a prime.

It is a super-2 number, since 2×155312231² = 48243778196394722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 155312197 and 155312206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155312233) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1158980 + ... + 1159113.

It is an arithmetic number, because the mean of its divisors is an integer number (39407598).

Almost surely, 2^155312231 is an apocalyptic number.

155312231 is a deficient number, since it is larger than the sum of its proper divisors (2318161).

155312231 is an equidigital number, since it uses as much as digits as its factorization.

155312231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2318160.

The product of its digits is 900, while the sum is 23.

The square root of 155312231 is about 12462.4327881839. The cubic root of 155312231 is about 537.5289831856.

Adding to 155312231 its reverse (132213551), we get a palindrome (287525782).

The spelling of 155312231 in words is "one hundred fifty-five million, three hundred twelve thousand, two hundred thirty-one".