51663720 has 64 divisors (see below), whose sum is σ = 155675520. Its totient is φ = 13716224.

The previous prime is 51663707. The next prime is 51663737. The reversal of 51663720 is 2736615.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30742 + ... + 32378.

It is an arithmetic number, because the mean of its divisors is an integer number (2432430).

Almost surely, 2^51663720 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 51663720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77837760).

51663720 is an abundant number, since it is smaller than the sum of its proper divisors (104011800).

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

51663720 is a wasteful number, since it uses less digits than its factorization.

51663720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1914 (or 1910 counting only the distinct ones).

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 51663720 is about 7187.7479087681. The cubic root of 51663720 is about 372.4447795867. Note that the first 3 decimals are identical.

The spelling of 51663720 in words is "fifty-one million, six hundred sixty-three thousand, seven hundred twenty".