21554455253 has 4 divisors (see below), whose sum is σ = 21585204108. Its totient is φ = 21523706400.

The previous prime is 21554455231. The next prime is 21554455283. The reversal of 21554455253 is 35255445512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12210913009 + 9343542244 = 110503^2 + 96662^2 .

It is a cyclic number.

It is not a de Polignac number, because 21554455253 - 2⁶ = 21554455189 is a prime.

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 21554455253.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554455213) 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, 15373376 + ... + 15374777.

It is an arithmetic number, because the mean of its divisors is an integer number (5396301027).

Almost surely, 2^21554455253 is an apocalyptic number.

It is an amenable number.

21554455253 is a deficient number, since it is larger than the sum of its proper divisors (30748855).

21554455253 is an equidigital number, since it uses as much as digits as its factorization.

21554455253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30748854.

The product of its digits is 600000, while the sum is 41.

The spelling of 21554455253 in words is "twenty-one billion, five hundred fifty-four million, four hundred fifty-five thousand, two hundred fifty-three".