51215400 has 144 divisors (see below), whose sum is σ = 176876700. Its totient is φ = 13271040.

The previous prime is 51215377. The next prime is 51215419. The reversal of 51215400 is 451215.

51215400 is a `hidden beast` number, since 5 + 121 + 540 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 27185796 + 24029604 = 5214^2 + 4902^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 66216 + ... + 66984.

Almost surely, 2^51215400 is an apocalyptic number.

51215400 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51215400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88438350).

51215400 is an abundant number, since it is smaller than the sum of its proper divisors (125661300).

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

51215400 is a wasteful number, since it uses less digits than its factorization.

51215400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 828 (or 816 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 51215400 is about 7156.4935548074. The cubic root of 51215400 is about 371.3643323674.

Adding to 51215400 its reverse (451215), we get a palindrome (51666615).

It can be divided in two parts, 51215 and 400, that added together give a palindrome (51615).

The spelling of 51215400 in words is "fifty-one million, two hundred fifteen thousand, four hundred".