21010001009 has 16 divisors (see below), whose sum is σ = 21898619904. Its totient is φ = 20141395200.

The previous prime is 21010000967. The next prime is 21010001011. The reversal of 21010001009 is 90010001012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21010001009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010000984 and 21010001002.

It is not an unprimeable number, because it can be changed into a prime (21010001029) 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, 798152 + ... + 824054.

It is an arithmetic number, because the mean of its divisors is an integer number (1368663744).

Almost surely, 2^21010001009 is an apocalyptic number.

It is an amenable number.

21010001009 is a deficient number, since it is larger than the sum of its proper divisors (888618895).

21010001009 is a wasteful number, since it uses less digits than its factorization.

21010001009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26288.

The product of its (nonzero) digits is 18, while the sum is 14.

The spelling of 21010001009 in words is "twenty-one billion, ten million, one thousand, nine".