51721807 has 2 divisors, whose sum is σ = 51721808. Its totient is φ = 51721806.

The previous prime is 51721801. The next prime is 51721841. The reversal of 51721807 is 70812715.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51721807 - 2⁷ = 51721679 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51721801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25860903 + 25860904.

It is an arithmetic number, because the mean of its divisors is an integer number (25860904).

Almost surely, 2^51721807 is an apocalyptic number.

51721807 is a deficient number, since it is larger than the sum of its proper divisors (1).

51721807 is an equidigital number, since it uses as much as digits as its factorization.

51721807 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 51721807 is about 7191.7874690511. The cubic root of 51721807 is about 372.5843107509.

The spelling of 51721807 in words is "fifty-one million, seven hundred twenty-one thousand, eight hundred seven".