21429740 has 12 divisors (see below), whose sum is σ = 45002496. Its totient is φ = 8571888.

The previous prime is 21429731. The next prime is 21429743. The reversal of 21429740 is 4792412.

It is not an unprimeable number, because it can be changed into a prime (21429743) 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, 535724 + ... + 535763.

It is an arithmetic number, because the mean of its divisors is an integer number (3750208).

Almost surely, 2^21429740 is an apocalyptic number.

21429740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21429740 is an abundant number, since it is smaller than the sum of its proper divisors (23572756).

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

21429740 is a wasteful number, since it uses less digits than its factorization.

21429740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1071496 (or 1071494 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21429740 is about 4629.2267172823. The cubic root of 21429740 is about 277.7616610501.

The spelling of 21429740 in words is "twenty-one million, four hundred twenty-nine thousand, seven hundred forty".