17742721421 has 2 divisors, whose sum is σ = 17742721422. Its totient is φ = 17742721420.

The previous prime is 17742721363. The next prime is 17742721441. The reversal of 17742721421 is 12412724771.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17725993321 + 16728100 = 133139^2 + 4090^2 .

It is a cyclic number.

It is not a de Polignac number, because 17742721421 - 2¹⁸ = 17742459277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17742721441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8871360710 + 8871360711.

It is an arithmetic number, because the mean of its divisors is an integer number (8871360711).

Almost surely, 2^17742721421 is an apocalyptic number.

It is an amenable number.

17742721421 is a deficient number, since it is larger than the sum of its proper divisors (1).

17742721421 is an equidigital number, since it uses as much as digits as its factorization.

17742721421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43904, while the sum is 38.

The spelling of 17742721421 in words is "seventeen billion, seven hundred forty-two million, seven hundred twenty-one thousand, four hundred twenty-one".