51638309 has 2 divisors, whose sum is σ = 51638310. Its totient is φ = 51638308.

The previous prime is 51638303. The next prime is 51638339. The reversal of 51638309 is 90383615.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44930209 + 6708100 = 6703^2 + 2590^2 .

It is a cyclic number.

It is not a de Polignac number, because 51638309 - 2²⁴ = 34861093 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51638303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25819154 + 25819155.

It is an arithmetic number, because the mean of its divisors is an integer number (25819155).

Almost surely, 2^51638309 is an apocalyptic number.

It is an amenable number.

51638309 is a deficient number, since it is larger than the sum of its proper divisors (1).

51638309 is an equidigital number, since it uses as much as digits as its factorization.

51638309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 51638309 is about 7185.9800305873. The cubic root of 51638309 is about 372.3837067721.

The spelling of 51638309 in words is "fifty-one million, six hundred thirty-eight thousand, three hundred nine".