51225640 has 64 divisors (see below), whose sum is σ = 120384000. Its totient is φ = 19595520.

The previous prime is 51225637. The next prime is 51225659. The reversal of 51225640 is 4652215.

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, 134971 + ... + 135349.

It is an arithmetic number, because the mean of its divisors is an integer number (1881000).

Almost surely, 2^51225640 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 51225640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60192000).

51225640 is an abundant number, since it is smaller than the sum of its proper divisors (69158360).

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

51225640 is a wasteful number, since it uses less digits than its factorization.

51225640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530 (or 526 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 51225640 is about 7157.2089532163. The cubic root of 51225640 is about 371.3890808959.

Adding to 51225640 its reverse (4652215), we get a palindrome (55877855).

The spelling of 51225640 in words is "fifty-one million, two hundred twenty-five thousand, six hundred forty".