1721897129 has 2 divisors, whose sum is σ = 1721897130. Its totient is φ = 1721897128.

The previous prime is 1721897053. The next prime is 1721897141. The reversal of 1721897129 is 9217981271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1548579904 + 173317225 = 39352^2 + 13165^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1721897129 is a prime.

It is not a weakly prime, because it can be changed into another prime (1721857129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860948564 + 860948565.

It is an arithmetic number, because the mean of its divisors is an integer number (860948565).

Almost surely, 2^1721897129 is an apocalyptic number.

It is an amenable number.

1721897129 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721897129 is an equidigital number, since it uses as much as digits as its factorization.

1721897129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 47.

The square root of 1721897129 is about 41495.7483243766. The cubic root of 1721897129 is about 1198.5856320039.

The spelling of 1721897129 in words is "one billion, seven hundred twenty-one million, eight hundred ninety-seven thousand, one hundred twenty-nine".