21156547309 has 8 divisors (see below), whose sum is σ = 22614846912. Its totient is φ = 19743118560.

The previous prime is 21156547301. The next prime is 21156547331. The reversal of 21156547309 is 90374565112.

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

It is a cyclic number.

It is not a de Polignac number, because 21156547309 - 2³ = 21156547301 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156547301) 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, 11216739 + ... + 11218624.

It is an arithmetic number, because the mean of its divisors is an integer number (2826855864).

Almost surely, 2^21156547309 is an apocalyptic number.

It is an amenable number.

21156547309 is a deficient number, since it is larger than the sum of its proper divisors (1458299603).

21156547309 is a wasteful number, since it uses less digits than its factorization.

21156547309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22435427.

The product of its (nonzero) digits is 226800, while the sum is 43.

The spelling of 21156547309 in words is "twenty-one billion, one hundred fifty-six million, five hundred forty-seven thousand, three hundred nine".