21621406064521 has 8 divisors (see below), whose sum is σ = 21733888908800. Its totient is φ = 21508927909632.

The previous prime is 21621406064483. The next prime is 21621406064539. The reversal of 21621406064521 is 12546060412612.

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 21621406064521 - 2²¹ = 21621403967369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21621406064821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8270356 + ... + 10566058.

It is an arithmetic number, because the mean of its divisors is an integer number (2716736113600).

Almost surely, 2^{21621406064521} is an apocalyptic number.

It is an amenable number.

21621406064521 is a deficient number, since it is larger than the sum of its proper divisors (112482844279).

21621406064521 is a wasteful number, since it uses less digits than its factorization.

21621406064521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2344695.

The product of its (nonzero) digits is 138240, while the sum is 40.

The spelling of 21621406064521 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred six million, sixty-four thousand, five hundred twenty-one".