21121101 has 8 divisors (see below), whose sum is σ = 31290560. Its totient is φ = 14080716.

The previous prime is 21121099. The next prime is 21121129. The reversal of 21121101 is 10112112.

It is a happy number.

It is not a de Polignac number, because 21121101 - 2¹ = 21121099 is a prime.

It is a super-2 number, since 2×21121101² = 892201814904402, which contains 22 as substring.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121171) 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, 391105 + ... + 391158.

It is an arithmetic number, because the mean of its divisors is an integer number (3911320).

Almost surely, 2^21121101 is an apocalyptic number.

It is an amenable number.

21121101 is a deficient number, since it is larger than the sum of its proper divisors (10169459).

21121101 is an equidigital number, since it uses as much as digits as its factorization.

21121101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 782272 (or 782266 counting only the distinct ones).

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

The square root of 21121101 is about 4595.7699028563. The cubic root of 21121101 is about 276.4217323846.

Adding to 21121101 its reverse (10112112), we get a palindrome (31233213).

It can be divided in two parts, 211 and 21101, that added together give a palindrome (21312).

The spelling of 21121101 in words is "twenty-one million, one hundred twenty-one thousand, one hundred one".