21436040 has 32 divisors (see below), whose sum is σ = 48384000. Its totient is φ = 8547264.

The previous prime is 21436027. The next prime is 21436067. The reversal of 21436040 is 4063412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a plaindrome in base 11.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16121 + ... + 17399.

It is an arithmetic number, because the mean of its divisors is an integer number (1512000).

Almost surely, 2^21436040 is an apocalyptic number.

21436040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21436040 is an abundant number, since it is smaller than the sum of its proper divisors (26947960).

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

21436040 is a wasteful number, since it uses less digits than its factorization.

21436040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1709 (or 1705 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 21436040 is about 4629.9071264983. The cubic root of 21436040 is about 277.7888775416.

Adding to 21436040 its reverse (4063412), we get a palindrome (25499452).

The spelling of 21436040 in words is "twenty-one million, four hundred thirty-six thousand, forty".