51866921 has 2 divisors, whose sum is σ = 51866922. Its totient is φ = 51866920.

The previous prime is 51866869. The next prime is 51866923. The reversal of 51866921 is 12966815.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27709696 + 24157225 = 5264^2 + 4915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51866921 is a prime.

Together with 51866923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (51866923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25933460 + 25933461.

It is an arithmetic number, because the mean of its divisors is an integer number (25933461).

Almost surely, 2^51866921 is an apocalyptic number.

It is an amenable number.

51866921 is a deficient number, since it is larger than the sum of its proper divisors (1).

51866921 is an equidigital number, since it uses as much as digits as its factorization.

51866921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 38.

The square root of 51866921 is about 7201.8692712378. The cubic root of 51866921 is about 372.9324341484.

The spelling of 51866921 in words is "fifty-one million, eight hundred sixty-six thousand, nine hundred twenty-one".