21213121110 has 64 divisors (see below), whose sum is σ = 51418920960. Its totient is φ = 5600534400.

The previous prime is 21213121093. The next prime is 21213121123. The reversal of 21213121110 is 1112131212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21213121110.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8314335 + ... + 8316885.

It is an arithmetic number, because the mean of its divisors is an integer number (803420640).

Almost surely, 2^21213121110 is an apocalyptic number.

21213121110 is an abundant number, since it is smaller than the sum of its proper divisors (30205799850).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21213121110 is a wasteful number, since it uses less digits than its factorization.

21213121110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5213.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21213121110 its reverse (1112131212), we get a palindrome (22325252322).

The spelling of 21213121110 in words is "twenty-one billion, two hundred thirteen million, one hundred twenty-one thousand, one hundred ten".