51172220 has 48 divisors (see below), whose sum is σ = 118032768. Its totient is φ = 18480960.

The previous prime is 51172133. The next prime is 51172249. The reversal of 51172220 is 2227115.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 51172192 and 51172201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35147 + ... + 36573.

It is an arithmetic number, because the mean of its divisors is an integer number (2459016).

Almost surely, 2^51172220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51172220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (59016384).

51172220 is an abundant number, since it is smaller than the sum of its proper divisors (66860548).

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

51172220 is a wasteful number, since it uses less digits than its factorization.

51172220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1610 (or 1608 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 51172220 is about 7153.4760781036. The cubic root of 51172220 is about 371.2599365508.

Adding to 51172220 its reverse (2227115), we get a palindrome (53399335).

It can be divided in two parts, 5117 and 2220, that added together give a palindrome (7337).

The spelling of 51172220 in words is "fifty-one million, one hundred seventy-two thousand, two hundred twenty".