1721281651 has 2 divisors, whose sum is σ = 1721281652. Its totient is φ = 1721281650.

The previous prime is 1721281643. The next prime is 1721281669. The reversal of 1721281651 is 1561821271.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1721281651 - 2³ = 1721281643 is a prime.

It is not a weakly prime, because it can be changed into another prime (1721285651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860640825 + 860640826.

It is an arithmetic number, because the mean of its divisors is an integer number (860640826).

Almost surely, 2^1721281651 is an apocalyptic number.

1721281651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721281651 is an equidigital number, since it uses as much as digits as its factorization.

1721281651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 34.

The square root of 1721281651 is about 41488.3315041711. The cubic root of 1721281651 is about 1198.4428067855.

The spelling of 1721281651 in words is "one billion, seven hundred twenty-one million, two hundred eighty-one thousand, six hundred fifty-one".