51615640 has 64 divisors (see below), whose sum is σ = 120022560. Its totient is φ = 19968000.

The previous prime is 51615607. The next prime is 51615643. The reversal of 51615640 is 4651615.

51615640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 51615599 and 51615608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51615643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 205515 + ... + 205765.

Almost surely, 2^51615640 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 51615640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60011280).

51615640 is an abundant number, since it is smaller than the sum of its proper divisors (68406920).

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

51615640 is a wasteful number, since it uses less digits than its factorization.

51615640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412 (or 408 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 51615640 is about 7184.4025499689. The cubic root of 51615640 is about 372.3292071704.

It can be divided in two parts, 5161 and 5640, that added together give a palindrome (10801).

The spelling of 51615640 in words is "fifty-one million, six hundred fifteen thousand, six hundred forty".