21555054427 has 2 divisors, whose sum is σ = 21555054428. Its totient is φ = 21555054426.

The previous prime is 21555054383. The next prime is 21555054467. The reversal of 21555054427 is 72445055512.

It is a happy number.

It is an a-pointer prime, because the next prime (21555054467) can be obtained adding 21555054427 to its sum of digits (40).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21555054427 - 2¹⁵ = 21555021659 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21555054427.

It is not a weakly prime, because it can be changed into another prime (21555054467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777527213 + 10777527214.

It is an arithmetic number, because the mean of its divisors is an integer number (10777527214).

Almost surely, 2^21555054427 is an apocalyptic number.

21555054427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21555054427 is an equidigital number, since it uses as much as digits as its factorization.

21555054427 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 280000, while the sum is 40.

The spelling of 21555054427 in words is "twenty-one billion, five hundred fifty-five million, fifty-four thousand, four hundred twenty-seven".