21001012011 has 12 divisors (see below), whose sum is σ = 34668337392. Its totient is φ = 12000578256.

The previous prime is 21001012007. The next prime is 21001012049. The reversal of 21001012011 is 11021010012.

It is a happy number.

It is not a de Polignac number, because 21001012011 - 2² = 21001012007 is a prime.

It is a super-3 number, since 3×21001012011³ (a number of 32 digits) contains 333 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 21001011984 and 21001012002.

It is not an unprimeable number, because it can be changed into a prime (21001012051) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166674636 + ... + 166674761.

It is an arithmetic number, because the mean of its divisors is an integer number (2889028116).

Almost surely, 2^21001012011 is an apocalyptic number.

21001012011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21001012011 is a deficient number, since it is larger than the sum of its proper divisors (13667325381).

21001012011 is a wasteful number, since it uses less digits than its factorization.

21001012011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333349410 (or 333349407 counting only the distinct ones).

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

Adding to 21001012011 its reverse (11021010012), we get a palindrome (32022022023).

The spelling of 21001012011 in words is "twenty-one billion, one million, twelve thousand, eleven".