51709240 has 128 divisors (see below), whose sum is σ = 139345920. Its totient is φ = 17049600.

The previous prime is 51709211. The next prime is 51709253. The reversal of 51709240 is 4290715.

It is a happy number.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 51709199 and 51709208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 231769 + ... + 231991.

It is an arithmetic number, because the mean of its divisors is an integer number (1088640).

Almost surely, 2^51709240 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 51709240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (69672960).

51709240 is an abundant number, since it is smaller than the sum of its proper divisors (87636680).

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

51709240 is a wasteful number, since it uses less digits than its factorization.

51709240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293 (or 289 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 51709240 is about 7190.9137110662. The cubic root of 51709240 is about 372.5541323369.

Adding to 51709240 its reverse (4290715), we get a palindrome (55999955).

The spelling of 51709240 in words is "fifty-one million, seven hundred nine thousand, two hundred forty".