1020921409 has 4 divisors (see below), whose sum is σ = 1023226416. Its totient is φ = 1018616404.

The previous prime is 1020921373. The next prime is 1020921413. The reversal of 1020921409 is 9041290201.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9041290201 = 19 ⋅475857379.

It is a cyclic number.

It is not a de Polignac number, because 1020921409 - 2⁹ = 1020920897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1020921469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1151839 + ... + 1152724.

It is an arithmetic number, because the mean of its divisors is an integer number (255806604).

Almost surely, 2^1020921409 is an apocalyptic number.

It is an amenable number.

1020921409 is a deficient number, since it is larger than the sum of its proper divisors (2305007).

1020921409 is an equidigital number, since it uses as much as digits as its factorization.

1020921409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2305006.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 1020921409 is about 31951.8608065321. The cubic root of 1020921409 is about 1006.9257265789.

The spelling of 1020921409 in words is "one billion, twenty million, nine hundred twenty-one thousand, four hundred nine".