51500021 has 16 divisors (see below), whose sum is σ = 57047040. Its totient is φ = 46275840.

The previous prime is 51500011. The next prime is 51500023. The reversal of 51500021 is 12000515.

It is a cyclic number.

It is not a de Polignac number, because 51500021 - 2⁶ = 51499957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 51499969 and 51500005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51500023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41015 + ... + 42251.

It is an arithmetic number, because the mean of its divisors is an integer number (3565440).

Almost surely, 2^51500021 is an apocalyptic number.

It is an amenable number.

51500021 is a deficient number, since it is larger than the sum of its proper divisors (5547019).

51500021 is a wasteful number, since it uses less digits than its factorization.

51500021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1364.

The product of its (nonzero) digits is 50, while the sum is 14.

The square root of 51500021 is about 7176.3515103428. The cubic root of 51500021 is about 372.0509936069.

Adding to 51500021 its reverse (12000515), we get a palindrome (63500536).

The spelling of 51500021 in words is "fifty-one million, five hundred thousand, twenty-one".