21221282730 has 32 divisors (see below), whose sum is σ = 52687324800. Its totient is φ = 5463870272.

The previous prime is 21221282669. The next prime is 21221282737. The reversal of 21221282730 is 3728212212.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21221282737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12195270 + ... + 12197009.

It is an arithmetic number, because the mean of its divisors is an integer number (1646478900).

Almost surely, 2^21221282730 is an apocalyptic number.

21221282730 is an abundant number, since it is smaller than the sum of its proper divisors (31466042070).

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

21221282730 is a wasteful number, since it uses less digits than its factorization.

21221282730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24392318.

The product of its (nonzero) digits is 5376, while the sum is 30.

Adding to 21221282730 its reverse (3728212212), we get a palindrome (24949494942).

The spelling of 21221282730 in words is "twenty-one billion, two hundred twenty-one million, two hundred eighty-two thousand, seven hundred thirty".