1629648721 has 2 divisors, whose sum is σ = 1629648722. Its totient is φ = 1629648720.

The previous prime is 1629648667. The next prime is 1629648751. The reversal of 1629648721 is 1278469261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1616040000 + 13608721 = 40200^2 + 3689^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1629648721 is a prime.

It is not a weakly prime, because it can be changed into another prime (1629648751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 814824360 + 814824361.

It is an arithmetic number, because the mean of its divisors is an integer number (814824361).

Almost surely, 2^1629648721 is an apocalyptic number.

It is an amenable number.

1629648721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1629648721 is an equidigital number, since it uses as much as digits as its factorization.

1629648721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 46.

The square root of 1629648721 is about 40368.9078499778. The cubic root of 1629648721 is about 1176.7873738232.

The spelling of 1629648721 in words is "one billion, six hundred twenty-nine million, six hundred forty-eight thousand, seven hundred twenty-one".