2591515721 has 2 divisors, whose sum is σ = 2591515722. Its totient is φ = 2591515720.

The previous prime is 2591515699. The next prime is 2591515747. The reversal of 2591515721 is 1275151952.

2591515721 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., 2156209225 + 435306496 = 46435^2 + 20864^2 .

It is a cyclic number.

It is not a de Polignac number, because 2591515721 - 2²² = 2587321417 is a prime.

It is not a weakly prime, because it can be changed into another prime (2591514721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1295757860 + 1295757861.

It is an arithmetic number, because the mean of its divisors is an integer number (1295757861).

Almost surely, 2^2591515721 is an apocalyptic number.

It is an amenable number.

2591515721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2591515721 is an equidigital number, since it uses as much as digits as its factorization.

2591515721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31500, while the sum is 38.

The square root of 2591515721 is about 50906.9319543026. The cubic root of 2591515721 is about 1373.5715361879.

The spelling of 2591515721 in words is "two billion, five hundred ninety-one million, five hundred fifteen thousand, seven hundred twenty-one".