21555054439 has 4 divisors (see below), whose sum is σ = 21610466280. Its totient is φ = 21499642600.

The previous prime is 21555054427. The next prime is 21555054467. The reversal of 21555054439 is 93445055512.

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

It is a cyclic number.

It is not a de Polignac number, because 21555054439 - 2²³ = 21546665831 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21555054395 and 21555054404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21555054539) 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, 27705337 + ... + 27706114.

It is an arithmetic number, because the mean of its divisors is an integer number (5402616570).

Almost surely, 2^21555054439 is an apocalyptic number.

21555054439 is a deficient number, since it is larger than the sum of its proper divisors (55411841).

21555054439 is an equidigital number, since it uses as much as digits as its factorization.

21555054439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55411840.

The product of its (nonzero) digits is 540000, while the sum is 43.

The spelling of 21555054439 in words is "twenty-one billion, five hundred fifty-five million, fifty-four thousand, four hundred thirty-nine".