1647420121 has 2 divisors, whose sum is σ = 1647420122. Its totient is φ = 1647420120.

The previous prime is 1647420113. The next prime is 1647420157. The reversal of 1647420121 is 1210247461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1249976025 + 397444096 = 35355^2 + 19936^2 .

It is a cyclic number.

It is not a de Polignac number, because 1647420121 - 2³ = 1647420113 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1647420121.

It is not a weakly prime, because it can be changed into another prime (1647421121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823710060 + 823710061.

It is an arithmetic number, because the mean of its divisors is an integer number (823710061).

Almost surely, 2^1647420121 is an apocalyptic number.

It is an amenable number.

1647420121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1647420121 is an equidigital number, since it uses as much as digits as its factorization.

1647420121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 1647420121 is about 40588.4234850283. The cubic root of 1647420121 is about 1181.0495595775.

Adding to 1647420121 its reverse (1210247461), we get a palindrome (2857667582).

The spelling of 1647420121 in words is "one billion, six hundred forty-seven million, four hundred twenty thousand, one hundred twenty-one".