21002403544 has 16 divisors (see below), whose sum is σ = 39416360400. Its totient is φ = 10491374112.

The previous prime is 21002403529. The next prime is 21002403553. The reversal of 21002403544 is 44530420012.

It is a happy number.

It is a super-2 number, since 2×21002403544² (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 in 3 ways as a sum of consecutive naturals, for example, 1219372 + ... + 1236475.

It is an arithmetic number, because the mean of its divisors is an integer number (2463522525).

Almost surely, 2^21002403544 is an apocalyptic number.

It is an amenable number.

21002403544 is a deficient number, since it is larger than the sum of its proper divisors (18413956856).

21002403544 is a wasteful number, since it uses less digits than its factorization.

21002403544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2456922 (or 2456918 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 25.

Adding to 21002403544 its reverse (44530420012), we get a palindrome (65532823556).

The spelling of 21002403544 in words is "twenty-one billion, two million, four hundred three thousand, five hundred forty-four".