15583721 has 2 divisors, whose sum is σ = 15583722. Its totient is φ = 15583720.

The previous prime is 15583699. The next prime is 15583723. The reversal of 15583721 is 12738551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8185321 + 7398400 = 2861^2 + 2720^2 .

It is a cyclic number.

It is not a de Polignac number, because 15583721 - 2⁶ = 15583657 is a prime.

Together with 15583723, 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 (15583723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7791860 + 7791861.

It is an arithmetic number, because the mean of its divisors is an integer number (7791861).

Almost surely, 2^15583721 is an apocalyptic number.

It is an amenable number.

15583721 is a deficient number, since it is larger than the sum of its proper divisors (1).

15583721 is an equidigital number, since it uses as much as digits as its factorization.

15583721 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 15583721 is about 3947.6221957021. The cubic root of 15583721 is about 249.7796511760.

The spelling of 15583721 in words is "fifteen million, five hundred eighty-three thousand, seven hundred twenty-one".