123651721 has 2 divisors, whose sum is σ = 123651722. Its totient is φ = 123651720.

The previous prime is 123651629. The next prime is 123651751. The reversal of 123651721 is 127156321.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 95942025 + 27709696 = 9795^2 + 5264^2 .

It is a cyclic number.

It is not a de Polignac number, because 123651721 - 2²¹ = 121554569 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 123651721.

It is not a weakly prime, because it can be changed into another prime (123651751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61825860 + 61825861.

It is an arithmetic number, because the mean of its divisors is an integer number (61825861).

Almost surely, 2^123651721 is an apocalyptic number.

It is an amenable number.

123651721 is a deficient number, since it is larger than the sum of its proper divisors (1).

123651721 is an equidigital number, since it uses as much as digits as its factorization.

123651721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520, while the sum is 28.

The square root of 123651721 is about 11119.8795407145. The cubic root of 123651721 is about 498.1957921655.

The spelling of 123651721 in words is "one hundred twenty-three million, six hundred fifty-one thousand, seven hundred twenty-one".