221131231020 has 72 divisors (see below), whose sum is σ = 766588271904. Its totient is φ = 50544281088.

The previous prime is 221131231001. The next prime is 221131231127. The reversal of 221131231020 is 20132131122.

221131231020 is a `hidden beast` number, since 2 + 21 + 1 + 312 + 310 + 20 = 666.

It is a super-2 number, since 2×221131231020² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 221131230984 and 221131231002.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 87749229 + ... + 87751748.

It is an arithmetic number, because the mean of its divisors is an integer number (10647059332).

Almost surely, 2^221131231020 is an apocalyptic number.

221131231020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221131231020 is an abundant number, since it is smaller than the sum of its proper divisors (545457040884).

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

221131231020 is a wasteful number, since it uses less digits than its factorization.

221131231020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175500999 (or 175500994 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 221131231020 its reverse (20132131122), we get a palindrome (241263362142).

The spelling of 221131231020 in words is "two hundred twenty-one billion, one hundred thirty-one million, two hundred thirty-one thousand, twenty".