51340721 has 2 divisors, whose sum is σ = 51340722. Its totient is φ = 51340720.

The previous prime is 51340699. The next prime is 51340741. The reversal of 51340721 is 12704315.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50566321 + 774400 = 7111^2 + 880^2 .

It is a cyclic number.

It is not a de Polignac number, because 51340721 - 2²² = 47146417 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (51340741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25670360 + 25670361.

It is an arithmetic number, because the mean of its divisors is an integer number (25670361).

Almost surely, 2^51340721 is an apocalyptic number.

It is an amenable number.

51340721 is a deficient number, since it is larger than the sum of its proper divisors (1).

51340721 is an equidigital number, since it uses as much as digits as its factorization.

51340721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 51340721 is about 7165.2439595592. The cubic root of 51340721 is about 371.6669876953. Note that the first 3 decimals are identical.

The spelling of 51340721 in words is "fifty-one million, three hundred forty thousand, seven hundred twenty-one".