1231865172 has 72 divisors (see below), whose sum is σ = 3308078592. Its totient is φ = 400593600.

The previous prime is 1231865137. The next prime is 1231865179. The reversal of 1231865172 is 2715681321.

1231865172 is a `hidden beast` number, since 123 + 18 + 6 + 517 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231865179) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24397 + ... + 55307.

It is an arithmetic number, because the mean of its divisors is an integer number (45945536).

Almost surely, 2^1231865172 is an apocalyptic number.

1231865172 is a gapful number since it is divisible by the number (12) 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 1231865172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1654039296).

1231865172 is an abundant number, since it is smaller than the sum of its proper divisors (2076213420).

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

1231865172 is a wasteful number, since it uses less digits than its factorization.

1231865172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30971 (or 30957 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 1231865172 is about 35097.9368624425. The cubic root of 1231865172 is about 1071.9825740187.

The spelling of 1231865172 in words is "one billion, two hundred thirty-one million, eight hundred sixty-five thousand, one hundred seventy-two".