51720637 has 2 divisors, whose sum is σ = 51720638. Its totient is φ = 51720636.

The previous prime is 51720607. The next prime is 51720673. The reversal of 51720637 is 73602715.

Together with next prime (51720673) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41550916 + 10169721 = 6446^2 + 3189^2 .

It is a cyclic number.

It is not a de Polignac number, because 51720637 - 2⁷ = 51720509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51720599 and 51720608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51720607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25860318 + 25860319.

It is an arithmetic number, because the mean of its divisors is an integer number (25860319).

Almost surely, 2^51720637 is an apocalyptic number.

It is an amenable number.

51720637 is a deficient number, since it is larger than the sum of its proper divisors (1).

51720637 is an equidigital number, since it uses as much as digits as its factorization.

51720637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8820, while the sum is 31.

The square root of 51720637 is about 7191.7061258091. The cubic root of 51720637 is about 372.5815013174.

The spelling of 51720637 in words is "fifty-one million, seven hundred twenty thousand, six hundred thirty-seven".