21206154454 has 4 divisors (see below), whose sum is σ = 31809231684. Its totient is φ = 10603077226.

The previous prime is 21206154419. The next prime is 21206154479. The reversal of 21206154454 is 45445160212.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5301538612 + ... + 5301538615.

It is an arithmetic number, because the mean of its divisors is an integer number (7952307921).

Almost surely, 2^21206154454 is an apocalyptic number.

21206154454 is a deficient number, since it is larger than the sum of its proper divisors (10603077230).

21206154454 is a wasteful number, since it uses less digits than its factorization.

21206154454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10603077229.

The product of its (nonzero) digits is 38400, while the sum is 34.

The spelling of 21206154454 in words is "twenty-one billion, two hundred six million, one hundred fifty-four thousand, four hundred fifty-four".