128447821 has 2 divisors, whose sum is σ = 128447822. Its totient is φ = 128447820.

The previous prime is 128447797. The next prime is 128447827. The reversal of 128447821 is 128744821.

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., 109620900 + 18826921 = 10470^2 + 4339^2 .

It is a cyclic number.

It is not a de Polignac number, because 128447821 - 2¹³ = 128439629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128447827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64223910 + 64223911.

It is an arithmetic number, because the mean of its divisors is an integer number (64223911).

Almost surely, 2^128447821 is an apocalyptic number.

It is an amenable number.

128447821 is a deficient number, since it is larger than the sum of its proper divisors (1).

128447821 is an equidigital number, since it uses as much as digits as its factorization.

128447821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28672, while the sum is 37.

The square root of 128447821 is about 11333.4822980406. The cubic root of 128447821 is about 504.5554641119. Note that the first 3 decimals are identical.

The spelling of 128447821 in words is "one hundred twenty-eight million, four hundred forty-seven thousand, eight hundred twenty-one".