21430340 has 24 divisors (see below), whose sum is σ = 46052160. Its totient is φ = 8372448.

The previous prime is 21430327. The next prime is 21430369. The reversal of 21430340 is 4303412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11600 + ... + 13319.

It is an arithmetic number, because the mean of its divisors is an integer number (1918840).

Almost surely, 2^21430340 is an apocalyptic number.

21430340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21430340 is an abundant number, since it is smaller than the sum of its proper divisors (24621820).

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

21430340 is a wasteful number, since it uses less digits than its factorization.

21430340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24971 (or 24969 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21430340 is about 4629.2915224686. The cubic root of 21430340 is about 277.7642533267.

Adding to 21430340 its reverse (4303412), we get a palindrome (25733752).

The spelling of 21430340 in words is "twenty-one million, four hundred thirty thousand, three hundred forty".