21155110720 has 56 divisors (see below), whose sum is σ = 53026970400. Its totient is φ = 8016671232.

The previous prime is 21155110693. The next prime is 21155110747. The reversal of 21155110720 is 2701155112.

It is an interprime number because it is at equal distance from previous prime (21155110693) and next prime (21155110747).

It is a congruent number.

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, 1733650 + ... + 1745809.

Almost surely, 2^21155110720 is an apocalyptic number.

21155110720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21155110720 is an abundant number, since it is smaller than the sum of its proper divisors (31871859680).

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

21155110720 is a wasteful number, since it uses less digits than its factorization.

21155110720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3479495 (or 3479485 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 25.

Adding to 21155110720 its reverse (2701155112), we get a palindrome (23856265832).

The spelling of 21155110720 in words is "twenty-one billion, one hundred fifty-five million, one hundred ten thousand, seven hundred twenty".