21121111210 has 8 divisors (see below), whose sum is σ = 38018000196. Its totient is φ = 8448444480.

The previous prime is 21121111153. The next prime is 21121111279. The reversal of 21121111210 is 1211112112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 18331264449 + 2789846761 = 135393^2 + 52819^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21121111210² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1056055551 + ... + 1056055570.

Almost surely, 2^21121111210 is an apocalyptic number.

21121111210 is a deficient number, since it is larger than the sum of its proper divisors (16896888986).

21121111210 is a wasteful number, since it uses less digits than its factorization.

21121111210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2112111128.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21121111210 its reverse (1211112112), we get a palindrome (22332223322).

The spelling of 21121111210 in words is "twenty-one billion, one hundred twenty-one million, one hundred eleven thousand, two hundred ten".