21651404543 has 4 divisors (see below), whose sum is σ = 21781053840. Its totient is φ = 21521755248.

The previous prime is 21651404519. The next prime is 21651404557. The reversal of 21651404543 is 34540415612.

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 21651404543 - 2⁸ = 21651404287 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21651404503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64824398 + ... + 64824731.

It is an arithmetic number, because the mean of its divisors is an integer number (5445263460).

Almost surely, 2^21651404543 is an apocalyptic number.

21651404543 is a deficient number, since it is larger than the sum of its proper divisors (129649297).

21651404543 is a wasteful number, since it uses less digits than its factorization.

21651404543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129649296.

The product of its (nonzero) digits is 57600, while the sum is 35.

The spelling of 21651404543 in words is "twenty-one billion, six hundred fifty-one million, four hundred four thousand, five hundred forty-three".