51271720 has 32 divisors (see below), whose sum is σ = 117258120. Its totient is φ = 20171520.

The previous prime is 51271699. The next prime is 51271721. The reversal of 51271720 is 2717215.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8421604 + 42850116 = 2902^2 + 6546^2 .

It is a Smith number, since the sum of its digits (25) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (51271721) 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, 8067 + ... + 12946.

Almost surely, 2^51271720 is an apocalyptic number.

It is an amenable number.

51271720 is an abundant number, since it is smaller than the sum of its proper divisors (65986400).

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

51271720 is a wasteful number, since it uses less digits than its factorization.

51271720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21085 (or 21081 counting only the distinct ones).

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 51271720 is about 7160.4273615476. The cubic root of 51271720 is about 371.5004084778.

Adding to 51271720 its reverse (2717215), we get a palindrome (53988935).

The spelling of 51271720 in words is "fifty-one million, two hundred seventy-one thousand, seven hundred twenty".