1647652421 has 2 divisors, whose sum is σ = 1647652422. Its totient is φ = 1647652420.

The previous prime is 1647652381. The next prime is 1647652423. The reversal of 1647652421 is 1242567461.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1647223396 + 429025 = 40586^2 + 655^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1647652421 is a prime.

It is a super-2 number, since 2×1647652421² = 5429517000854322482, which contains 22 as substring.

Together with 1647652423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1647652423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823826210 + 823826211.

It is an arithmetic number, because the mean of its divisors is an integer number (823826211).

Almost surely, 2^1647652421 is an apocalyptic number.

It is an amenable number.

1647652421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1647652421 is an equidigital number, since it uses as much as digits as its factorization.

1647652421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 38.

The square root of 1647652421 is about 40591.2850375546. The cubic root of 1647652421 is about 1181.1050695867.

The spelling of 1647652421 in words is "one billion, six hundred forty-seven million, six hundred fifty-two thousand, four hundred twenty-one".