21155516040040 has 32 divisors (see below), whose sum is σ = 47667047841000. Its totient is φ = 8450270993664.

The previous prime is 21155516040019. The next prime is 21155516040067. The reversal of 21155516040040 is 4004061555112.

It can be written as a sum of positive squares in 4 ways, for example, as 13865807637124 + 7289708402916 = 3723682^2 + 2699946^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21155516039978 and 21155516040005.

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, 372953235 + ... + 373009954.

Almost surely, 2^{21155516040040} is an apocalyptic number.

21155516040040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21155516040040 is an abundant number, since it is smaller than the sum of its proper divisors (26511531800960).

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

21155516040040 is a wasteful number, since it uses less digits than its factorization.

21155516040040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 745963909 (or 745963905 counting only the distinct ones).

The product of its (nonzero) digits is 24000, while the sum is 34.

Adding to 21155516040040 its reverse (4004061555112), we get a palindrome (25159577595152).

The spelling of 21155516040040 in words is "twenty-one trillion, one hundred fifty-five billion, five hundred sixteen million, forty thousand, forty".