51997780 has 12 divisors (see below), whose sum is σ = 109195380. Its totient is φ = 20799104.

The previous prime is 51997739. The next prime is 51997787. The reversal of 51997780 is 8779915.

It can be written as a sum of positive squares in 2 ways, for example, as 30338064 + 21659716 = 5508^2 + 4654^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 51997780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51997787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1299925 + ... + 1299964.

It is an arithmetic number, because the mean of its divisors is an integer number (9099615).

Almost surely, 2^51997780 is an apocalyptic number.

It is an amenable number.

51997780 is an abundant number, since it is smaller than the sum of its proper divisors (57197600).

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

51997780 is a wasteful number, since it uses less digits than its factorization.

51997780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2599898 (or 2599896 counting only the distinct ones).

The product of its (nonzero) digits is 158760, while the sum is 46.

The square root of 51997780 is about 7210.9486199806. The cubic root of 51997780 is about 373.2458039556.

The spelling of 51997780 in words is "fifty-one million, nine hundred ninety-seven thousand, seven hundred eighty".