21121012009 has 8 divisors (see below), whose sum is σ = 22259160000. Its totient is φ = 19985515632.

The previous prime is 21121011959. The next prime is 21121012021. The reversal of 21121012009 is 90021012112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21121012009 - 2¹⁹ = 21120487721 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121012049) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 646534 + ... + 678415.

It is an arithmetic number, because the mean of its divisors is an integer number (2782395000).

Almost surely, 2^21121012009 is an apocalyptic number.

It is an amenable number.

21121012009 is a deficient number, since it is larger than the sum of its proper divisors (1138147991).

21121012009 is a wasteful number, since it uses less digits than its factorization.

21121012009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1325807.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21121012009 in words is "twenty-one billion, one hundred twenty-one million, twelve thousand, nine".