6418437721 has 2 divisors, whose sum is σ = 6418437722. Its totient is φ = 6418437720.

The previous prime is 6418437691. The next prime is 6418437743. The reversal of 6418437721 is 1277348146.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5411073600 + 1007364121 = 73560^2 + 31739^2 .

It is a cyclic number.

It is not a de Polignac number, because 6418437721 - 2⁵ = 6418437689 is a prime.

It is not a weakly prime, because it can be changed into another prime (6418437791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3209218860 + 3209218861.

It is an arithmetic number, because the mean of its divisors is an integer number (3209218861).

Almost surely, 2^6418437721 is an apocalyptic number.

It is an amenable number.

6418437721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6418437721 is an equidigital number, since it uses as much as digits as its factorization.

6418437721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 43.

The square root of 6418437721 is about 80115.1528800888. The cubic root of 6418437721 is about 1858.4167473740.

The spelling of 6418437721 in words is "six billion, four hundred eighteen million, four hundred thirty-seven thousand, seven hundred twenty-one".