21215120 has 40 divisors (see below), whose sum is σ = 49516920. Its totient is φ = 8453120.

The previous prime is 21215111. The next prime is 21215137. The reversal of 21215120 is 2151212.

It can be written as a sum of positive squares in 4 ways, for example, as 2930944 + 18284176 = 1712^2 + 4276^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×21215120² = 900162633228800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21215095 and 21215104.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40460 + ... + 40980.

It is an arithmetic number, because the mean of its divisors is an integer number (1237923).

Almost surely, 2^21215120 is an apocalyptic number.

21215120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21215120 is an abundant number, since it is smaller than the sum of its proper divisors (28301800).

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

21215120 is a wasteful number, since it uses less digits than its factorization.

21215120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1043 (or 1037 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21215120 is about 4605.9874077118. The cubic root of 21215120 is about 276.8312821741.

Adding to 21215120 its reverse (2151212), we get a palindrome (23366332).

The spelling of 21215120 in words is "twenty-one million, two hundred fifteen thousand, one hundred twenty".