51201720 has 80 divisors (see below), whose sum is σ = 172105560. Its totient is φ = 13652928.

The previous prime is 51201649. The next prime is 51201727. The reversal of 51201720 is 2710215.

It is a super-2 number, since 2×51201720² = 5243232261916800, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 51201693 and 51201702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51201727) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4662 + ... + 11141.

Almost surely, 2^51201720 is an apocalyptic number.

It is an amenable number.

51201720 is an abundant number, since it is smaller than the sum of its proper divisors (120903840).

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

51201720 is a wasteful number, since it uses less digits than its factorization.

51201720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15826 (or 15813 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 51201720 is about 7155.5377156437. The cubic root of 51201720 is about 371.3312647325.

Adding to 51201720 its reverse (2710215), we get a palindrome (53911935).

The spelling of 51201720 in words is "fifty-one million, two hundred one thousand, seven hundred twenty".