21111002001 has 16 divisors (see below), whose sum is σ = 31386870720. Its totient is φ = 14023910880.

The previous prime is 21111001993. The next prime is 21111002039. The reversal of 21111002001 is 10020011112.

It is a happy number.

It is not a de Polignac number, because 21111002001 - 2³ = 21111001993 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21111002501) 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, 1383675 + ... + 1398848.

It is an arithmetic number, because the mean of its divisors is an integer number (1961679420).

Almost surely, 2^21111002001 is an apocalyptic number.

It is an amenable number.

21111002001 is a deficient number, since it is larger than the sum of its proper divisors (10275868719).

21111002001 is a wasteful number, since it uses less digits than its factorization.

21111002001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2782813 (or 2782807 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21111002001 its reverse (10020011112), we get a palindrome (31131013113).

The spelling of 21111002001 in words is "twenty-one billion, one hundred eleven million, two thousand, one".