1021604021 has 2 divisors, whose sum is σ = 1021604022. Its totient is φ = 1021604020.

The previous prime is 1021603997. The next prime is 1021604029. The reversal of 1021604021 is 1204061201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 687226225 + 334377796 = 26215^2 + 18286^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021604021 - 2¹⁰ = 1021602997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1021604029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510802010 + 510802011.

It is an arithmetic number, because the mean of its divisors is an integer number (510802011).

Almost surely, 2^1021604021 is an apocalyptic number.

It is an amenable number.

1021604021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021604021 is an equidigital number, since it uses as much as digits as its factorization.

1021604021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 1021604021 is about 31962.5409033763. The cubic root of 1021604021 is about 1007.1500946333.

Adding to 1021604021 its reverse (1204061201), we get a palindrome (2225665222).

The spelling of 1021604021 in words is "one billion, twenty-one million, six hundred four thousand, twenty-one".