1021439899 has 4 divisors (see below), whose sum is σ = 1024926336. Its totient is φ = 1017953464.

The previous prime is 1021439897. The next prime is 1021439911. The reversal of 1021439899 is 9989341201.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1021439899 - 2¹ = 1021439897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1021439891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1742779 + ... + 1743364.

It is an arithmetic number, because the mean of its divisors is an integer number (256231584).

Almost surely, 2^1021439899 is an apocalyptic number.

1021439899 is a deficient number, since it is larger than the sum of its proper divisors (3486437).

1021439899 is an equidigital number, since it uses as much as digits as its factorization.

1021439899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3486436.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 1021439899 is about 31959.9733885997. The cubic root of 1021439899 is about 1007.0961584255.

The spelling of 1021439899 in words is "one billion, twenty-one million, four hundred thirty-nine thousand, eight hundred ninety-nine".