21309519651 has 8 divisors (see below), whose sum is σ = 32471649024. Its totient is φ = 12176868360.

The previous prime is 21309519617. The next prime is 21309519701. The reversal of 21309519651 is 15691590312.

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

It is not a de Polignac number, because 21309519651 - 2⁹ = 21309519139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21309517651) 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 7 ways as a sum of consecutive naturals, for example, 507369495 + ... + 507369536.

It is an arithmetic number, because the mean of its divisors is an integer number (4058956128).

Almost surely, 2^21309519651 is an apocalyptic number.

21309519651 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21309519651 is a deficient number, since it is larger than the sum of its proper divisors (11162129373).

21309519651 is a wasteful number, since it uses less digits than its factorization.

21309519651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1014739041.

The product of its (nonzero) digits is 72900, while the sum is 42.

The spelling of 21309519651 in words is "twenty-one billion, three hundred nine million, five hundred nineteen thousand, six hundred fifty-one".