21121525161544 has 8 divisors (see below), whose sum is σ = 39602859677910. Its totient is φ = 10560762580768.

The previous prime is 21121525161533. The next prime is 21121525161613. The reversal of 21121525161544 is 44516152512112.

It can be written as a sum of positive squares in only one way, i.e., 21120366576100 + 1158585444 = 4595690^2 + 34038^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21121525161544² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121525161497 and 21121525161506.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1320095322589 + ... + 1320095322604.

Almost surely, 2^{21121525161544} is an apocalyptic number.

It is an amenable number.

21121525161544 is a deficient number, since it is larger than the sum of its proper divisors (18481334516366).

21121525161544 is a wasteful number, since it uses less digits than its factorization.

21121525161544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2640190645199 (or 2640190645195 counting only the distinct ones).

The product of its digits is 96000, while the sum is 40.

Adding to 21121525161544 its reverse (44516152512112), we get a palindrome (65637677673656).

The spelling of 21121525161544 in words is "twenty-one trillion, one hundred twenty-one billion, five hundred twenty-five million, one hundred sixty-one thousand, five hundred forty-four".