21506567609 has 8 divisors (see below), whose sum is σ = 22652664480. Its totient is φ = 20361888000.

The previous prime is 21506567573. The next prime is 21506567623. The reversal of 21506567609 is 90676560512.

It is a happy number.

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 21506567609 - 2¹² = 21506563513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21506567629) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 323087 + ... + 383924.

It is an arithmetic number, because the mean of its divisors is an integer number (2831583060).

Almost surely, 2^21506567609 is an apocalyptic number.

It is an amenable number.

21506567609 is a deficient number, since it is larger than the sum of its proper divisors (1146096871).

21506567609 is a wasteful number, since it uses less digits than its factorization.

21506567609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708631.

The product of its (nonzero) digits is 680400, while the sum is 47.

The spelling of 21506567609 in words is "twenty-one billion, five hundred six million, five hundred sixty-seven thousand, six hundred nine".