21069940 has 12 divisors (see below), whose sum is σ = 44246916. Its totient is φ = 8427968.

The previous prime is 21069929. The next prime is 21069943. The reversal of 21069940 is 4996012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 4210704 + 16859236 = 2052^2 + 4106^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21069943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 526729 + ... + 526768.

It is an arithmetic number, because the mean of its divisors is an integer number (3687243).

Almost surely, 2^21069940 is an apocalyptic number.

21069940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21069940 is an abundant number, since it is smaller than the sum of its proper divisors (23176976).

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

21069940 is a wasteful number, since it uses less digits than its factorization.

21069940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1053506 (or 1053504 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 21069940 is about 4590.2004313537. The cubic root of 21069940 is about 276.1983626176.

The spelling of 21069940 in words is "twenty-one million, sixty-nine thousand, nine hundred forty".