51321240 has 48 divisors (see below), whose sum is σ = 166795200. Its totient is φ = 13685568.

The previous prime is 51321203. The next prime is 51321241. The reversal of 51321240 is 4212315.

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

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51321241) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 70920 + ... + 71639.

It is an arithmetic number, because the mean of its divisors is an integer number (3474900).

Almost surely, 2^51321240 is an apocalyptic number.

It is an amenable number.

51321240 is an abundant number, since it is smaller than the sum of its proper divisors (115473960).

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

51321240 is a wasteful number, since it uses less digits than its factorization.

51321240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142576 (or 142569 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 51321240 is about 7163.8844211782. The cubic root of 51321240 is about 371.6199726396.

Adding to 51321240 its reverse (4212315), we get a palindrome (55533555).

The spelling of 51321240 in words is "fifty-one million, three hundred twenty-one thousand, two hundred forty".