21507574243545 has 80 divisors (see below), whose sum is σ = 42104825021952. Its totient is φ = 10439212452480.

The previous prime is 21507574243541. The next prime is 21507574243621. The reversal of 21507574243545 is 54534247570512.

21507574243545 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 7 + 5 + 74 + 24 + 3 + 545 = 666.

It is not a de Polignac number, because 21507574243545 - 2² = 21507574243541 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21507574243491 and 21507574243500.

It is not an unprimeable number, because it can be changed into a prime (21507574243541) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 28393857 + ... + 29141486.

Almost surely, 2^{21507574243545} is an apocalyptic number.

It is an amenable number.

21507574243545 is a deficient number, since it is larger than the sum of its proper divisors (20597250778407).

21507574243545 is a wasteful number, since it uses less digits than its factorization.

21507574243545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57535444 (or 57535435 counting only the distinct ones).

The product of its (nonzero) digits is 23520000, while the sum is 54.

The spelling of 21507574243545 in words is "twenty-one trillion, five hundred seven billion, five hundred seventy-four million, two hundred forty-three thousand, five hundred forty-five".