21155020306 has 16 divisors (see below), whose sum is σ = 36269867520. Its totient is φ = 9065407680.

The previous prime is 21155020283. The next prime is 21155020319. The reversal of 21155020306 is 60302055112.

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, 49210 + ... + 211498.

It is an arithmetic number, because the mean of its divisors is an integer number (2266866720).

Almost surely, 2^21155020306 is an apocalyptic number.

21155020306 is a deficient number, since it is larger than the sum of its proper divisors (15114847214).

21155020306 is a wasteful number, since it uses less digits than its factorization.

21155020306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171609.

The product of its (nonzero) digits is 1800, while the sum is 25.

Adding to 21155020306 its reverse (60302055112), we get a palindrome (81457075418).

The spelling of 21155020306 in words is "twenty-one billion, one hundred fifty-five million, twenty thousand, three hundred six".