66547437021 has 24 divisors (see below), whose sum is σ = 108019032576. Its totient is φ = 39171733920.

The previous prime is 66547436951. The next prime is 66547437031. The reversal of 66547437021 is 12073474566.

66547437021 is a `hidden beast` number, since 66 + 547 + 43 + 7 + 0 + 2 + 1 = 666.

It is not a de Polignac number, because 66547437021 - 2⁹ = 66547436509 is a prime.

It is a super-2 number, since 2×66547437021² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66547437031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12362125 + ... + 12367506.

It is an arithmetic number, because the mean of its divisors is an integer number (4500793024).

Almost surely, 2^66547437021 is an apocalyptic number.

It is an amenable number.

66547437021 is a deficient number, since it is larger than the sum of its proper divisors (41471595555).

66547437021 is a wasteful number, since it uses less digits than its factorization.

66547437021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24729673 (or 24729670 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 45.

The spelling of 66547437021 in words is "sixty-six billion, five hundred forty-seven million, four hundred thirty-seven thousand, twenty-one".