51781356 has 144 divisors (see below), whose sum is σ = 154103040. Its totient is φ = 15059520.

The previous prime is 51781343. The next prime is 51781361. The reversal of 51781356 is 65318715.

51781356 is a `hidden beast` number, since 517 + 8 + 135 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 51781356.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 309985 + ... + 310151.

It is an arithmetic number, because the mean of its divisors is an integer number (1070160).

Almost surely, 2^51781356 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 51781356, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77051520).

51781356 is an abundant number, since it is smaller than the sum of its proper divisors (102321684).

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

51781356 is a wasteful number, since it uses less digits than its factorization.

51781356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226 (or 212 counting only the distinct ones).

The product of its digits is 25200, while the sum is 36.

The square root of 51781356 is about 7195.9263475942. The cubic root of 51781356 is about 372.7272453914.

The spelling of 51781356 in words is "fifty-one million, seven hundred eighty-one thousand, three hundred fifty-six".