21121011 has 6 divisors (see below), whose sum is σ = 30508140. Its totient is φ = 14080668.

The previous prime is 21121003. The next prime is 21121033. The reversal of 21121011 is 11012112.

It is a happy number.

It is not a de Polignac number, because 21121011 - 2³ = 21121003 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 2346779 = 21121011 / (2 + 1 + 1 + 2 + 1 + 0 + 1 + 1).

It is a junction number, because it is equal to n+sod(n) for n = 21120984 and 21121002.

It is not an unprimeable number, because it can be changed into a prime (21121081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1173381 + ... + 1173398.

It is an arithmetic number, because the mean of its divisors is an integer number (5084690).

Almost surely, 2^21121011 is an apocalyptic number.

21121011 is a deficient number, since it is larger than the sum of its proper divisors (9387129).

21121011 is a wasteful number, since it uses less digits than its factorization.

21121011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2346785 (or 2346782 counting only the distinct ones).

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

The square root of 21121011 is about 4595.7601112330. The cubic root of 21121011 is about 276.4213397600.

Adding to 21121011 its reverse (11012112), we get a palindrome (32133123).

The spelling of 21121011 in words is "twenty-one million, one hundred twenty-one thousand, eleven".