21257154455 has 4 divisors (see below), whose sum is σ = 25508585352. Its totient is φ = 17005723560.

The previous prime is 21257154439. The next prime is 21257154473. The reversal of 21257154455 is 55445175212.

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

It is not a de Polignac number, because 21257154455 - 2⁴ = 21257154439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2125715441 + ... + 2125715450.

It is an arithmetic number, because the mean of its divisors is an integer number (6377146338).

Almost surely, 2^21257154455 is an apocalyptic number.

21257154455 is a deficient number, since it is larger than the sum of its proper divisors (4251430897).

21257154455 is an equidigital number, since it uses as much as digits as its factorization.

21257154455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4251430896.

The product of its digits is 280000, while the sum is 41.

The spelling of 21257154455 in words is "twenty-one billion, two hundred fifty-seven million, one hundred fifty-four thousand, four hundred fifty-five".