154815721 has 2 divisors, whose sum is σ = 154815722. Its totient is φ = 154815720.

The previous prime is 154815709. The next prime is 154815751. The reversal of 154815721 is 127518451.

154815721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 107412496 + 47403225 = 10364^2 + 6885^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-154815721 is a prime.

It is not a weakly prime, because it can be changed into another prime (154815751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77407860 + 77407861.

It is an arithmetic number, because the mean of its divisors is an integer number (77407861).

Almost surely, 2^154815721 is an apocalyptic number.

It is an amenable number.

154815721 is a deficient number, since it is larger than the sum of its proper divisors (1).

154815721 is an equidigital number, since it uses as much as digits as its factorization.

154815721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11200, while the sum is 34.

The square root of 154815721 is about 12442.4965742410. The cubic root of 154815721 is about 536.9555717619.

The spelling of 154815721 in words is "one hundred fifty-four million, eight hundred fifteen thousand, seven hundred twenty-one".