65721251 has 2 divisors, whose sum is σ = 65721252. Its totient is φ = 65721250.

The previous prime is 65721241. The next prime is 65721263. The reversal of 65721251 is 15212756.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65721251 is a prime.

It is not a weakly prime, because it can be changed into another prime (65721211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32860625 + 32860626.

It is an arithmetic number, because the mean of its divisors is an integer number (32860626).

Almost surely, 2^65721251 is an apocalyptic number.

65721251 is the 3626-th centered decagonal number.

65721251 is a deficient number, since it is larger than the sum of its proper divisors (1).

65721251 is an equidigital number, since it uses as much as digits as its factorization.

65721251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4200, while the sum is 29.

The square root of 65721251 is about 8106.8644370065. The cubic root of 65721251 is about 403.5542640586.

The spelling of 65721251 in words is "sixty-five million, seven hundred twenty-one thousand, two hundred fifty-one".