21432730 has 24 divisors (see below), whose sum is σ = 42407316. Its totient is φ = 7793280.

The previous prime is 21432701. The next prime is 21432737. The reversal of 21432730 is 3723412.

It can be written as a sum of positive squares in 2 ways, for example, as 20638849 + 793881 = 4543^2 + 891^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21432737) 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 11 ways as a sum of consecutive naturals, for example, 7647 + ... + 10066.

Almost surely, 2^21432730 is an apocalyptic number.

21432730 is a deficient number, since it is larger than the sum of its proper divisors (20974586).

21432730 is a wasteful number, since it uses less digits than its factorization.

21432730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17742 (or 17731 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 22.

The square root of 21432730 is about 4629.5496541240. The cubic root of 21432730 is about 277.7745787483.

The spelling of 21432730 in words is "twenty-one million, four hundred thirty-two thousand, seven hundred thirty".