21203503444 has 6 divisors (see below), whose sum is σ = 37106131034. Its totient is φ = 10601751720.

The previous prime is 21203503421. The next prime is 21203503481. The reversal of 21203503444 is 44430530212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 16192562500 + 5010940944 = 127250^2 + 70788^2 .

It is a super-2 number, since 2×21203503444² (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, 2650437927 + ... + 2650437934.

Almost surely, 2^21203503444 is an apocalyptic number.

It is an amenable number.

21203503444 is a deficient number, since it is larger than the sum of its proper divisors (15902627590).

21203503444 is a wasteful number, since it uses less digits than its factorization.

21203503444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5300875865 (or 5300875863 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 28.

The spelling of 21203503444 in words is "twenty-one billion, two hundred three million, five hundred three thousand, four hundred forty-four".