21012164220 has 96 divisors (see below), whose sum is σ = 65573625600. Its totient is φ = 4996076544.

The previous prime is 21012164213. The next prime is 21012164227. The reversal of 21012164220 is 2246121012.

It is an interprime number because it is at equal distance from previous prime (21012164213) and next prime (21012164227).

It is a super-2 number, since 2×21012164220² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012164227) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 522730 + ... + 561489.

It is an arithmetic number, because the mean of its divisors is an integer number (683058600).

Almost surely, 2^21012164220 is an apocalyptic number.

21012164220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012164220 is an abundant number, since it is smaller than the sum of its proper divisors (44561461380).

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

21012164220 is a wasteful number, since it uses less digits than its factorization.

21012164220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1084267 (or 1084265 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

Adding to 21012164220 its reverse (2246121012), we get a palindrome (23258285232).

It can be divided in two parts, 2101 and 2164220, that added together give a triangular number (2166321 = T₂₀₈₁).

The spelling of 21012164220 in words is "twenty-one billion, twelve million, one hundred sixty-four thousand, two hundred twenty".