1721015761 has 2 divisors, whose sum is σ = 1721015762. Its totient is φ = 1721015760.

The previous prime is 1721015749. The next prime is 1721015767. The reversal of 1721015761 is 1675101271.

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., 1561751361 + 159264400 = 39519^2 + 12620^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721015761 - 2⁹ = 1721015249 is a prime.

It is a super-2 number, since 2×1721015761² = 5923790499220818242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1721015767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860507880 + 860507881.

It is an arithmetic number, because the mean of its divisors is an integer number (860507881).

Almost surely, 2^1721015761 is an apocalyptic number.

It is an amenable number.

1721015761 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721015761 is an equidigital number, since it uses as much as digits as its factorization.

1721015761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2940, while the sum is 31.

The square root of 1721015761 is about 41485.1269854631. The cubic root of 1721015761 is about 1198.3810949468.

The spelling of 1721015761 in words is "one billion, seven hundred twenty-one million, fifteen thousand, seven hundred sixty-one".