21829249921 has 4 divisors (see below), whose sum is σ = 21831088132. Its totient is φ = 21827411712.

The previous prime is 21829249909. The next prime is 21829249963. The reversal of 21829249921 is 12994292812.

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 15906254400 + 5922995521 = 126120^2 + 76961^2 .

It is a cyclic number.

It is not a de Polignac number, because 21829249921 - 2¹³ = 21829241729 is a prime.

It is a super-2 number, since 2×21829249921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21829249991) 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, 901176 + ... + 925081.

It is an arithmetic number, because the mean of its divisors is an integer number (5457772033).

Almost surely, 2^21829249921 is an apocalyptic number.

It is an amenable number.

21829249921 is a deficient number, since it is larger than the sum of its proper divisors (1838211).

21829249921 is a wasteful number, since it uses less digits than its factorization.

21829249921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1838210.

The product of its digits is 373248, while the sum is 49.

The spelling of 21829249921 in words is "twenty-one billion, eight hundred twenty-nine million, two hundred forty-nine thousand, nine hundred twenty-one".