6437475721 has 2 divisors, whose sum is σ = 6437475722. Its totient is φ = 6437475720.

The previous prime is 6437475719. The next prime is 6437475739. The reversal of 6437475721 is 1275747346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6371232400 + 66243321 = 79820^2 + 8139^2 .

It is a cyclic number.

It is not a de Polignac number, because 6437475721 - 2¹ = 6437475719 is a prime.

Together with 6437475719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (6437475791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3218737860 + 3218737861.

It is an arithmetic number, because the mean of its divisors is an integer number (3218737861).

Almost surely, 2^6437475721 is an apocalyptic number.

It is an amenable number.

6437475721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6437475721 is an equidigital number, since it uses as much as digits as its factorization.

6437475721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 987840, while the sum is 46.

The square root of 6437475721 is about 80233.8813781310. The cubic root of 6437475721 is about 1860.2523765341.

The spelling of 6437475721 in words is "six billion, four hundred thirty-seven million, four hundred seventy-five thousand, seven hundred twenty-one".