21004121344 has 18 divisors (see below), whose sum is σ = 41926195850. Its totient is φ = 10502060544.

The previous prime is 21004121329. The next prime is 21004121357. The reversal of 21004121344 is 44312140012.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13061746944 + 7942374400 = 114288^2 + 89120^2 .

It is a super-2 number, since 2×21004121344² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41023419 + ... + 41023930.

Almost surely, 2^21004121344 is an apocalyptic number.

It is an amenable number.

21004121344 is a deficient number, since it is larger than the sum of its proper divisors (20922074506).

21004121344 is an frugal number, since it uses more digits than its factorization.

21004121344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82047365 (or 82047351 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

Adding to 21004121344 its reverse (44312140012), we get a palindrome (65316261356).

The spelling of 21004121344 in words is "twenty-one billion, four million, one hundred twenty-one thousand, three hundred forty-four".