1724138921 has 2 divisors, whose sum is σ = 1724138922. Its totient is φ = 1724138920.

The previous prime is 1724138917. The next prime is 1724138947. The reversal of 1724138921 is 1298314271.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1311236521 + 412902400 = 36211^2 + 20320^2 .

It is a cyclic number.

It is not a de Polignac number, because 1724138921 - 2² = 1724138917 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1724138951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 862069460 + 862069461.

It is an arithmetic number, because the mean of its divisors is an integer number (862069461).

Almost surely, 2^1724138921 is an apocalyptic number.

It is an amenable number.

1724138921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1724138921 is an equidigital number, since it uses as much as digits as its factorization.

1724138921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 38.

The square root of 1724138921 is about 41522.7518476317. The cubic root of 1724138921 is about 1199.1055652006.

The spelling of 1724138921 in words is "one billion, seven hundred twenty-four million, one hundred thirty-eight thousand, nine hundred twenty-one".