21004061666440 has 32 divisors (see below), whose sum is σ = 47261833004160. Its totient is φ = 8401145688000.

The previous prime is 21004061666437. The next prime is 21004061666443. The reversal of 21004061666440 is 4466616040012.

It is an interprime number because it is at equal distance from previous prime (21004061666437) and next prime (21004061666443).

It is a super-2 number, since 2×21004061666440² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 21004061666393 and 21004061666402.

It is not an unprimeable number, because it can be changed into a prime (21004061666443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14257266 + ... + 15661345.

It is an arithmetic number, because the mean of its divisors is an integer number (1476932281380).

Almost surely, 2^{21004061666440} is an apocalyptic number.

21004061666440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21004061666440 is an abundant number, since it is smaller than the sum of its proper divisors (26257771337720).

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

21004061666440 is a wasteful number, since it uses less digits than its factorization.

21004061666440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29936173 (or 29936169 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 40.

The spelling of 21004061666440 in words is "twenty-one trillion, four billion, sixty-one million, six hundred sixty-six thousand, four hundred forty".