21352040 has 16 divisors (see below), whose sum is σ = 48042180. Its totient is φ = 8540800.

The previous prime is 21352039. The next prime is 21352049. The reversal of 21352040 is 4025312.

It can be written as a sum of positive squares in 2 ways, for example, as 19518724 + 1833316 = 4418^2 + 1354^2 .

It is a super-2 number, since 2×21352040² = 911819224323200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21352049) 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, 266861 + ... + 266940.

Almost surely, 2^21352040 is an apocalyptic number.

21352040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21352040 is an abundant number, since it is smaller than the sum of its proper divisors (26690140).

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

21352040 is a wasteful number, since it uses less digits than its factorization.

21352040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533812 (or 533808 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21352040 is about 4620.8267658505. The cubic root of 21352040 is about 277.4255515460.

Adding to 21352040 its reverse (4025312), we get a palindrome (25377352).

The spelling of 21352040 in words is "twenty-one million, three hundred fifty-two thousand, forty".