154561721 has 2 divisors, whose sum is σ = 154561722. Its totient is φ = 154561720.

The previous prime is 154561711. The next prime is 154561733. The reversal of 154561721 is 127165451.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 153264400 + 1297321 = 12380^2 + 1139^2 .

It is a cyclic number.

It is not a de Polignac number, because 154561721 - 2²² = 150367417 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (154561711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77280860 + 77280861.

It is an arithmetic number, because the mean of its divisors is an integer number (77280861).

Almost surely, 2^154561721 is an apocalyptic number.

It is an amenable number.

154561721 is a deficient number, since it is larger than the sum of its proper divisors (1).

154561721 is an equidigital number, since it uses as much as digits as its factorization.

154561721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8400, while the sum is 32.

The square root of 154561721 is about 12432.2854294776. The cubic root of 154561721 is about 536.6617571318.

The spelling of 154561721 in words is "one hundred fifty-four million, five hundred sixty-one thousand, seven hundred twenty-one".