251031020020 has 96 divisors (see below), whose sum is σ = 591983271936. Its totient is φ = 88637952000.

The previous prime is 251031019997. The next prime is 251031020021. The reversal of 251031020020 is 20020130152.

It is a junction number, because it is equal to n+sod(n) for n = 251031019976 and 251031020003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251031020021) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1020045 + ... + 1241995.

It is an arithmetic number, because the mean of its divisors is an integer number (6166492416).

Almost surely, 2^251031020020 is an apocalyptic number.

251031020020 is a gapful number since it is divisible by the number (20) 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 251031020020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (295991635968).

251031020020 is an abundant number, since it is smaller than the sum of its proper divisors (340952251916).

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

251031020020 is a wasteful number, since it uses less digits than its factorization.

251031020020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222121 (or 222119 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

Adding to 251031020020 its reverse (20020130152), we get a palindrome (271051150172).

The spelling of 251031020020 in words is "two hundred fifty-one billion, thirty-one million, twenty thousand, twenty".