8149721 has 2 divisors, whose sum is σ = 8149722. Its totient is φ = 8149720.

The previous prime is 8149703. The next prime is 8149723. The reversal of 8149721 is 1279418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8094025 + 55696 = 2845^2 + 236^2 .

It is a cyclic number.

It is not a de Polignac number, because 8149721 - 2²² = 3955417 is a prime.

Together with 8149723, 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 (8149723) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4074860 + 4074861.

It is an arithmetic number, because the mean of its divisors is an integer number (4074861).

Almost surely, 2^8149721 is an apocalyptic number.

It is an amenable number.

8149721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8149721 is an equidigital number, since it uses as much as digits as its factorization.

8149721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 8149721 is about 2854.7716195871. The cubic root of 8149721 is about 201.2399714664.

It can be divided in two parts, 81497 and 21, that added together give a palindrome (81518).

The spelling of 8149721 in words is "eight million, one hundred forty-nine thousand, seven hundred twenty-one".