21438991426 has 24 divisors (see below), whose sum is σ = 33636616524. Its totient is φ = 10247592960.

The previous prime is 21438991423. The next prime is 21438991429. The reversal of 21438991426 is 62419983412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21438991423) and next prime (21438991429).

It can be written as a sum of positive squares in 2 ways, for example, as 20896148025 + 542843401 = 144555^2 + 23299^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21438991426.

It is not an unprimeable number, because it can be changed into a prime (21438991421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2281650 + ... + 2291026.

Almost surely, 2^21438991426 is an apocalyptic number.

21438991426 is a deficient number, since it is larger than the sum of its proper divisors (12197625098).

21438991426 is a wasteful number, since it uses less digits than its factorization.

21438991426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11586 (or 11563 counting only the distinct ones).

The product of its digits is 746496, while the sum is 49.

The spelling of 21438991426 in words is "twenty-one billion, four hundred thirty-eight million, nine hundred ninety-one thousand, four hundred twenty-six".