1231531900 has 54 divisors (see below), whose sum is σ = 2710706712. Its totient is φ = 485654400.

The previous prime is 1231531843. The next prime is 1231531919. The reversal of 1231531900 is 91351321.

It is a super-2 number, since 2×1231531900² = 3033341641435220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 531745 + ... + 534055.

Almost surely, 2^1231531900 is an apocalyptic number.

1231531900 is a gapful number since it is divisible by the number (10) 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 1231531900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1355353356).

1231531900 is an abundant number, since it is smaller than the sum of its proper divisors (1479174812).

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

1231531900 is a wasteful number, since it uses less digits than its factorization.

1231531900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2471 (or 2391 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 25.

The square root of 1231531900 is about 35093.1887978280. The cubic root of 1231531900 is about 1071.8858929837.

The spelling of 1231531900 in words is "one billion, two hundred thirty-one million, five hundred thirty-one thousand, nine hundred".