21164040 has 48 divisors (see below), whose sum is σ = 68784300. Its totient is φ = 5643648.

The previous prime is 21164029. The next prime is 21164047. The reversal of 21164040 is 4046112.

21164040 is a `hidden beast` number, since 21 + 1 + 640 + 4 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19766916 + 1397124 = 4446^2 + 1182^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21164047) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29035 + ... + 29754.

Almost surely, 2^21164040 is an apocalyptic number.

21164040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21164040 is an abundant number, since it is smaller than the sum of its proper divisors (47620260).

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

21164040 is a wasteful number, since it uses less digits than its factorization.

21164040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58806 (or 58799 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21164040 is about 4600.4391094764. The cubic root of 21164040 is about 276.6089265160.

The spelling of 21164040 in words is "twenty-one million, one hundred sixty-four thousand, forty".