21629298521 has 4 divisors (see below), whose sum is σ = 21630220212. Its totient is φ = 21628376832.

The previous prime is 21629298503. The next prime is 21629298557. The reversal of 21629298521 is 12589292612.

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 20160876121 + 1468422400 = 141989^2 + 38320^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21629298521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21629298221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 424700 + ... + 472893.

It is an arithmetic number, because the mean of its divisors is an integer number (5407555053).

Almost surely, 2^21629298521 is an apocalyptic number.

It is an amenable number.

21629298521 is a deficient number, since it is larger than the sum of its proper divisors (921691).

21629298521 is an equidigital number, since it uses as much as digits as its factorization.

21629298521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 921690.

The product of its digits is 311040, while the sum is 47.

The spelling of 21629298521 in words is "twenty-one billion, six hundred twenty-nine million, two hundred ninety-eight thousand, five hundred twenty-one".