1209999021 has 64 divisors (see below), whose sum is σ = 2241976320. Its totient is φ = 560424960.

The previous prime is 1209999013. The next prime is 1209999023.

1209999021 is nontrivially palindromic in base 10.

1209999021 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1209999021 - 2³ = 1209999013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1209999023) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 66505 + ... + 82721.

It is an arithmetic number, because the mean of its divisors is an integer number (35030880).

Almost surely, 2^1209999021 is an apocalyptic number.

1209999021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1209999021 is a deficient number, since it is larger than the sum of its proper divisors (1031977299).

1209999021 is a wasteful number, since it uses less digits than its factorization.

1209999021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16274.

The product of its (nonzero) digits is 26244, while the sum is 42.

The square root of 1209999021 is about 34785.0401897137. The cubic root of 1209999021 is about 1065.6019493768.

The spelling of 1209999021 in words is "one billion, two hundred nine million, nine hundred ninety-nine thousand, twenty-one".