21629258509 has 4 divisors (see below), whose sum is σ = 21632980060. Its totient is φ = 21625536960.

The previous prime is 21629258477. The next prime is 21629258569. The reversal of 21629258509 is 90585292612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11484337225 + 10144921284 = 107165^2 + 100722^2 .

It is a cyclic number.

It is not a de Polignac number, because 21629258509 - 2⁵ = 21629258477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21629258569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1852044 + ... + 1863685.

It is an arithmetic number, because the mean of its divisors is an integer number (5408245015).

Almost surely, 2^21629258509 is an apocalyptic number.

It is an amenable number.

21629258509 is a deficient number, since it is larger than the sum of its proper divisors (3721551).

21629258509 is an equidigital number, since it uses as much as digits as its factorization.

21629258509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3721550.

The product of its (nonzero) digits is 777600, while the sum is 49.

The spelling of 21629258509 in words is "twenty-one billion, six hundred twenty-nine million, two hundred fifty-eight thousand, five hundred nine".