21040243442 has 32 divisors (see below), whose sum is σ = 32117258160. Its totient is φ = 10336435200.

The previous prime is 21040243397. The next prime is 21040243451. The reversal of 21040243442 is 24434204012.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 20921018881 + 119224561 = 144641^2 + 10919^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19249448 + ... + 19250540.

Almost surely, 2^21040243442 is an apocalyptic number.

21040243442 is a deficient number, since it is larger than the sum of its proper divisors (11077014718).

21040243442 is a wasteful number, since it uses less digits than its factorization.

21040243442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1838.

The product of its (nonzero) digits is 6144, while the sum is 26.

Adding to 21040243442 its reverse (24434204012), we get a palindrome (45474447454).

The spelling of 21040243442 in words is "twenty-one billion, forty million, two hundred forty-three thousand, four hundred forty-two".