21621516477557 has 8 divisors (see below), whose sum is σ = 21689056507392. Its totient is φ = 21553989811200.

The previous prime is 21621516477541. The next prime is 21621516477559. The reversal of 21621516477557 is 75577461512612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21621516477557 - 2⁴ = 21621516477541 is a prime.

It is a super-5 number, since 5×21621516477557⁵ (a number of 68 digits) contains 55555 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21621516477496 and 21621516477505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621516477559) 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 7 ways as a sum of consecutive naturals, for example, 94988 + ... + 6576629.

It is an arithmetic number, because the mean of its divisors is an integer number (2711132063424).

Almost surely, 2^{21621516477557} is an apocalyptic number.

It is an amenable number.

21621516477557 is a deficient number, since it is larger than the sum of its proper divisors (67540029835).

21621516477557 is an equidigital number, since it uses as much as digits as its factorization.

21621516477557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6681739.

The product of its digits is 24696000, while the sum is 59.

The spelling of 21621516477557 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred sixteen million, four hundred seventy-seven thousand, five hundred fifty-seven".