21021121209 has 16 divisors (see below), whose sum is σ = 30578938560. Its totient is φ = 12738922560.

The previous prime is 21021121201. The next prime is 21021121241. The reversal of 21021121209 is 90212112012.

It is not a de Polignac number, because 21021121209 - 2³ = 21021121201 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21021121201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 472287 + ... + 514875.

It is an arithmetic number, because the mean of its divisors is an integer number (1911183660).

Almost surely, 2^21021121209 is an apocalyptic number.

It is an amenable number.

21021121209 is a deficient number, since it is larger than the sum of its proper divisors (9557817351).

21021121209 is a wasteful number, since it uses less digits than its factorization.

21021121209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57560.

The product of its (nonzero) digits is 144, while the sum is 21.

The spelling of 21021121209 in words is "twenty-one billion, twenty-one million, one hundred twenty-one thousand, two hundred nine".