51161720 has 16 divisors (see below), whose sum is σ = 115113960. Its totient is φ = 20464672.

The previous prime is 51161707. The next prime is 51161731. The reversal of 51161720 is 2716115.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 639482 + ... + 639561.

Almost surely, 2^51161720 is an apocalyptic number.

It is an amenable number.

51161720 is an abundant number, since it is smaller than the sum of its proper divisors (63952240).

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

51161720 is a wasteful number, since it uses less digits than its factorization.

51161720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1279054 (or 1279050 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 23.

The square root of 51161720 is about 7152.7421315185. The cubic root of 51161720 is about 371.2345419389.

Adding to 51161720 its reverse (2716115), we get a palindrome (53877835).

The spelling of 51161720 in words is "fifty-one million, one hundred sixty-one thousand, seven hundred twenty".