51780399 has 32 divisors (see below), whose sum is σ = 79280640. Its totient is φ = 29769600.

The previous prime is 51780389. The next prime is 51780401. The reversal of 51780399 is 99308715.

It is a happy number.

It is not a de Polignac number, because 51780399 - 2⁵ = 51780367 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51780399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51780349) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 57934 + ... + 58820.

It is an arithmetic number, because the mean of its divisors is an integer number (2477520).

Almost surely, 2^51780399 is an apocalyptic number.

51780399 is a deficient number, since it is larger than the sum of its proper divisors (27500241).

51780399 is a wasteful number, since it uses less digits than its factorization.

51780399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991.

The product of its (nonzero) digits is 68040, while the sum is 42.

The square root of 51780399 is about 7195.8598513312. The cubic root of 51780399 is about 372.7249491842.

The spelling of 51780399 in words is "fifty-one million, seven hundred eighty thousand, three hundred ninety-nine".