21761404521 has 16 divisors (see below), whose sum is σ = 30016777728. Its totient is φ = 14008867200.

The previous prime is 21761404519. The next prime is 21761404559. The reversal of 21761404521 is 12540416712.

It is not a de Polignac number, because 21761404521 - 2¹ = 21761404519 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21761454521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 213510 + ... + 298511.

It is an arithmetic number, because the mean of its divisors is an integer number (1876048608).

Almost surely, 2^21761404521 is an apocalyptic number.

It is an amenable number.

21761404521 is a deficient number, since it is larger than the sum of its proper divisors (8255373207).

21761404521 is a wasteful number, since it uses less digits than its factorization.

21761404521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512512.

The product of its (nonzero) digits is 13440, while the sum is 33.

The spelling of 21761404521 in words is "twenty-one billion, seven hundred sixty-one million, four hundred four thousand, five hundred twenty-one".