21005764554 has 8 divisors (see below), whose sum is σ = 42011529120. Its totient is φ = 7001921516.

The previous prime is 21005764537. The next prime is 21005764589. The reversal of 21005764554 is 45546750012.

It is a sphenic number, since it is the product of 3 distinct primes.

21005764554 is an admirable 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, 1750480374 + ... + 1750480385.

It is an arithmetic number, because the mean of its divisors is an integer number (5251441140).

Almost surely, 2^21005764554 is an apocalyptic number.

21005764554 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21005764554 is a wasteful number, since it uses less digits than its factorization.

21005764554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3500960764.

The product of its (nonzero) digits is 168000, while the sum is 39.

The spelling of 21005764554 in words is "twenty-one billion, five million, seven hundred sixty-four thousand, five hundred fifty-four".