21153415547 has 4 divisors (see below), whose sum is σ = 23076453336. Its totient is φ = 19230377760.

The previous prime is 21153415511. The next prime is 21153415589. The reversal of 21153415547 is 74551435112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21153415547 - 2⁸ = 21153415291 is a prime.

It is a super-2 number, since 2×21153415547² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21153415547.

It is not an unprimeable number, because it can be changed into a prime (21153415147) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 961518878 + ... + 961518899.

It is an arithmetic number, because the mean of its divisors is an integer number (5769113334).

Almost surely, 2^21153415547 is an apocalyptic number.

21153415547 is a deficient number, since it is larger than the sum of its proper divisors (1923037789).

21153415547 is a wasteful number, since it uses less digits than its factorization.

21153415547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1923037788.

The product of its digits is 84000, while the sum is 38.

The spelling of 21153415547 in words is "twenty-one billion, one hundred fifty-three million, four hundred fifteen thousand, five hundred forty-seven".