21203740 has 12 divisors (see below), whose sum is σ = 44527896. Its totient is φ = 8481488.

The previous prime is 21203737. The next prime is 21203747. The reversal of 21203740 is 4730212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203747) 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 3 ways as a sum of consecutive naturals, for example, 530074 + ... + 530113.

It is an arithmetic number, because the mean of its divisors is an integer number (3710658).

Almost surely, 2^21203740 is an apocalyptic number.

21203740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21203740 is an abundant number, since it is smaller than the sum of its proper divisors (23324156).

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

21203740 is a wasteful number, since it uses less digits than its factorization.

21203740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1060196 (or 1060194 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 21203740 is about 4604.7518934249. The cubic root of 21203740 is about 276.7817749759.

Adding to 21203740 its reverse (4730212), we get a palindrome (25933952).

The spelling of 21203740 in words is "twenty-one million, two hundred three thousand, seven hundred forty".