251320020 has 144 divisors (see below), whose sum is σ = 830507328. Its totient is φ = 56609280.

The previous prime is 251320019. The next prime is 251320031. The reversal of 251320020 is 20023152.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 214035 + ... + 215205.

It is an arithmetic number, because the mean of its divisors is an integer number (5767412).

Almost surely, 2^251320020 is an apocalyptic number.

251320020 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 251320020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (415253664).

251320020 is an abundant number, since it is smaller than the sum of its proper divisors (579187308).

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

251320020 is a wasteful number, since it uses less digits than its factorization.

251320020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1270 (or 1261 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 251320020 is about 15853.0760422071. The cubic root of 251320020 is about 631.0673265496.

Adding to 251320020 its reverse (20023152), we get a palindrome (271343172).

The spelling of 251320020 in words is "two hundred fifty-one million, three hundred twenty thousand, twenty".