1974166721 has 2 divisors, whose sum is σ = 1974166722. Its totient is φ = 1974166720.

The previous prime is 1974166697. The next prime is 1974166741. The reversal of 1974166721 is 1276614791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1510410496 + 463756225 = 38864^2 + 21535^2 .

It is an emirp because it is prime and its reverse (1276614791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1974166721 - 2¹⁸ = 1973904577 is a prime.

It is not a weakly prime, because it can be changed into another prime (1974166741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 987083360 + 987083361.

It is an arithmetic number, because the mean of its divisors is an integer number (987083361).

Almost surely, 2^1974166721 is an apocalyptic number.

It is an amenable number.

1974166721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1974166721 is an equidigital number, since it uses as much as digits as its factorization.

1974166721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 44.

The square root of 1974166721 is about 44431.5959762870. The cubic root of 1974166721 is about 1254.4728760930.

The spelling of 1974166721 in words is "one billion, nine hundred seventy-four million, one hundred sixty-six thousand, seven hundred twenty-one".