21192730 has 16 divisors (see below), whose sum is σ = 41081544. Its totient is φ = 7824960.

The previous prime is 21192713. The next prime is 21192737. The reversal of 21192730 is 3729112.

It can be written as a sum of positive squares in 4 ways, for example, as 5248681 + 15944049 = 2291^2 + 3993^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21192695 and 21192704.

It is not an unprimeable number, because it can be changed into a prime (21192737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81381 + ... + 81640.

Almost surely, 2^21192730 is an apocalyptic number.

21192730 is a deficient number, since it is larger than the sum of its proper divisors (19888814).

21192730 is a wasteful number, since it uses less digits than its factorization.

21192730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163041.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21192730 is about 4603.5562340434. The cubic root of 21192730 is about 276.7338605523.

The spelling of 21192730 in words is "twenty-one million, one hundred ninety-two thousand, seven hundred thirty".