21209272509 has 16 divisors (see below), whose sum is σ = 30065323392. Its totient is φ = 13269567168.

The previous prime is 21209272507. The next prime is 21209272517. The reversal of 21209272509 is 90527290212.

It is not a de Polignac number, because 21209272509 - 2¹ = 21209272507 is a prime.

It is a super-2 number, since 2×21209272509² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21209272507) 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, 2896162 + ... + 2903475.

It is an arithmetic number, because the mean of its divisors is an integer number (1879082712).

Almost surely, 2^21209272509 is an apocalyptic number.

It is an amenable number.

21209272509 is a deficient number, since it is larger than the sum of its proper divisors (8856050883).

21209272509 is a wasteful number, since it uses less digits than its factorization.

21209272509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5799716.

The product of its (nonzero) digits is 45360, while the sum is 39.

The spelling of 21209272509 in words is "twenty-one billion, two hundred nine million, two hundred seventy-two thousand, five hundred nine".