21354540 has 24 divisors (see below), whose sum is σ = 59792880. Its totient is φ = 5694528.

The previous prime is 21354451. The next prime is 21354551. The reversal of 21354540 is 4545312.

It is a super-2 number, since 2×21354540² = 912032757223200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21354540.

It is an unprimeable number.

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, 177895 + ... + 178014.

It is an arithmetic number, because the mean of its divisors is an integer number (2491370).

Almost surely, 2^21354540 is an apocalyptic number.

21354540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21354540 is an abundant number, since it is smaller than the sum of its proper divisors (38438340).

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

21354540 is a wasteful number, since it uses less digits than its factorization.

21354540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355921 (or 355919 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 21354540 is about 4621.0972722937. The cubic root of 21354540 is about 277.4363785648.

Adding to 21354540 its reverse (4545312), we get a palindrome (25899852).

The spelling of 21354540 in words is "twenty-one million, three hundred fifty-four thousand, five hundred forty".