21517101947421 has 48 divisors (see below), whose sum is σ = 32502093062400. Its totient is φ = 13691226928896.

The previous prime is 21517101947377. The next prime is 21517101947503. The reversal of 21517101947421 is 12474910171512.

21517101947421 is a `hidden beast` number, since 2 + 1 + 5 + 171 + 0 + 1 + 9 + 474 + 2 + 1 = 666.

It is not a de Polignac number, because 21517101947421 - 2²¹ = 21517099850269 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21517101947021) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 577265241 + ... + 577302513.

It is an arithmetic number, because the mean of its divisors is an integer number (677126938800).

Almost surely, 2^{21517101947421} is an apocalyptic number.

It is an amenable number.

21517101947421 is a deficient number, since it is larger than the sum of its proper divisors (10984991114979).

21517101947421 is a wasteful number, since it uses less digits than its factorization.

21517101947421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43290 (or 43287 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 45.

The spelling of 21517101947421 in words is "twenty-one trillion, five hundred seventeen billion, one hundred one million, nine hundred forty-seven thousand, four hundred twenty-one".