21356040 has 32 divisors (see below), whose sum is σ = 64068480. Its totient is φ = 5694912.

The previous prime is 21356003. The next prime is 21356047. The reversal of 21356040 is 4065312.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21355998 and 21356016.

It is not an unprimeable number, because it can be changed into a prime (21356047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88864 + ... + 89103.

It is an arithmetic number, because the mean of its divisors is an integer number (2002140).

Almost surely, 2^21356040 is an apocalyptic number.

21356040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21356040 is an abundant number, since it is smaller than the sum of its proper divisors (42712440).

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

21356040 is a wasteful number, since it uses less digits than its factorization.

21356040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177981 (or 177977 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21356040 is about 4621.2595685592. The cubic root of 21356040 is about 277.4428743704.

The spelling of 21356040 in words is "twenty-one million, three hundred fifty-six thousand, forty".