21405551547 has 8 divisors (see below), whose sum is σ = 30219602256. Its totient is φ = 13430934272.

The previous prime is 21405551539. The next prime is 21405551591. The reversal of 21405551547 is 74515550412.

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 21405551547 - 2³ = 21405551539 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21405551537) 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, 209858298 + ... + 209858399.

It is an arithmetic number, because the mean of its divisors is an integer number (3777450282).

Almost surely, 2^21405551547 is an apocalyptic number.

21405551547 is a deficient number, since it is larger than the sum of its proper divisors (8814050709).

21405551547 is a wasteful number, since it uses less digits than its factorization.

21405551547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 419716717.

The product of its (nonzero) digits is 140000, while the sum is 39.

The spelling of 21405551547 in words is "twenty-one billion, four hundred five million, five hundred fifty-one thousand, five hundred forty-seven".