21405417420647 has 8 divisors (see below), whose sum is σ = 23280225497760. Its totient is φ = 19563214701600.

The previous prime is 21405417420551. The next prime is 21405417420659. The reversal of 21405417420647 is 74602471450412.

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 21405417420647 - 2⁸ = 21405417420391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405411420647) 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, 8151338147 + ... + 8151340772.

It is an arithmetic number, because the mean of its divisors is an integer number (2910028187220).

Almost surely, 2^{21405417420647} is an apocalyptic number.

21405417420647 is a deficient number, since it is larger than the sum of its proper divisors (1874808077113).

21405417420647 is a wasteful number, since it uses less digits than its factorization.

21405417420647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16302679033.

The product of its (nonzero) digits is 1505280, while the sum is 47.

The spelling of 21405417420647 in words is "twenty-one trillion, four hundred five billion, four hundred seventeen million, four hundred twenty thousand, six hundred forty-seven".