131801820 has 24 divisors (see below), whose sum is σ = 369045264. Its totient is φ = 35147136.

The previous prime is 131801777. The next prime is 131801821. The reversal of 131801820 is 28108131.

It is a super-4 number, since 4×131801820⁴ (a number of 34 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131801821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1098289 + ... + 1098408.

It is an arithmetic number, because the mean of its divisors is an integer number (15376886).

Almost surely, 2^131801820 is an apocalyptic number.

131801820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

131801820 is an abundant number, since it is smaller than the sum of its proper divisors (237243444).

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

131801820 is a wasteful number, since it uses less digits than its factorization.

131801820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2196709 (or 2196707 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 24.

The square root of 131801820 is about 11480.4973759851. The cubic root of 131801820 is about 508.9093957300.

Adding to 131801820 its reverse (28108131), we get a palindrome (159909951).

The spelling of 131801820 in words is "one hundred thirty-one million, eight hundred one thousand, eight hundred twenty".