21247730 has 16 divisors (see below), whose sum is σ = 43709760. Its totient is φ = 7284912.

The previous prime is 21247727. The next prime is 21247769. The reversal of 21247730 is 3774212.

It is a self number, because there is not a number n which added to its sum of digits gives 21247730.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151700 + ... + 151839.

It is an arithmetic number, because the mean of its divisors is an integer number (2731860).

Almost surely, 2^21247730 is an apocalyptic number.

21247730 is an abundant number, since it is smaller than the sum of its proper divisors (22462030).

21247730 is a wasteful number, since it uses less digits than its factorization.

21247730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 303553.

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 21247730 is about 4609.5260060011. The cubic root of 21247730 is about 276.9730497224.

The spelling of 21247730 in words is "twenty-one million, two hundred forty-seven thousand, seven hundred thirty".