51399940 has 48 divisors (see below), whose sum is σ = 118581120. Its totient is φ = 18627840.

The previous prime is 51399923. The next prime is 51399941. The reversal of 51399940 is 4999315.

It is a junction number, because it is equal to n+sod(n) for n = 51399893 and 51399902.

It is not an unprimeable number, because it can be changed into a prime (51399941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5800 + ... + 11680.

It is an arithmetic number, because the mean of its divisors is an integer number (2470440).

Almost surely, 2^51399940 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 51399940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (59290560).

51399940 is an abundant number, since it is smaller than the sum of its proper divisors (67181180).

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

51399940 is a wasteful number, since it uses less digits than its factorization.

51399940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5932 (or 5930 counting only the distinct ones).

The product of its (nonzero) digits is 43740, while the sum is 40.

The square root of 51399940 is about 7169.3751471101. The cubic root of 51399940 is about 371.8098326596.

The spelling of 51399940 in words is "fifty-one million, three hundred ninety-nine thousand, nine hundred forty".