1928401021 has 2 divisors, whose sum is σ = 1928401022. Its totient is φ = 1928401020.

The previous prime is 1928400961. The next prime is 1928401049. The reversal of 1928401021 is 1201048291.

It is an a-pointer prime, because the next prime (1928401049) can be obtained adding 1928401021 to its sum of digits (28).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1912312900 + 16088121 = 43730^2 + 4011^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1928401021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1928401721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 964200510 + 964200511.

It is an arithmetic number, because the mean of its divisors is an integer number (964200511).

Almost surely, 2^1928401021 is an apocalyptic number.

It is an amenable number.

1928401021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1928401021 is an equidigital number, since it uses as much as digits as its factorization.

1928401021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 1928401021 is about 43913.5630642743. The cubic root of 1928401021 is about 1244.7031374484.

The spelling of 1928401021 in words is "one billion, nine hundred twenty-eight million, four hundred one thousand, twenty-one".