21310040 has 16 divisors (see below), whose sum is σ = 47947680. Its totient is φ = 8524000.

The previous prime is 21310021. The next prime is 21310043. The reversal of 21310040 is 4001312.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310043) 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, 266336 + ... + 266415.

It is an arithmetic number, because the mean of its divisors is an integer number (2996730).

Almost surely, 2^21310040 is an apocalyptic number.

21310040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21310040 is an abundant number, since it is smaller than the sum of its proper divisors (26637640).

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

21310040 is a wasteful number, since it uses less digits than its factorization.

21310040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 532762 (or 532758 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21310040 is about 4616.2798875285. The cubic root of 21310040 is about 277.2435311338.

Adding to 21310040 its reverse (4001312), we get a palindrome (25311352).

The spelling of 21310040 in words is "twenty-one million, three hundred ten thousand, forty".