21745981634 has 16 divisors (see below), whose sum is σ = 35159619768. Its totient is φ = 10027608192.

The previous prime is 21745981619. The next prime is 21745981639. The reversal of 21745981634 is 43618954712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6544324609 + 15201657025 = 80897^2 + 123295^2 .

It is not an unprimeable number, because it can be changed into a prime (21745981639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 345347 + ... + 403430.

Almost surely, 2^21745981634 is an apocalyptic number.

21745981634 is a deficient number, since it is larger than the sum of its proper divisors (13413638134).

21745981634 is a wasteful number, since it uses less digits than its factorization.

21745981634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 749909.

The product of its digits is 1451520, while the sum is 50.

The spelling of 21745981634 in words is "twenty-one billion, seven hundred forty-five million, nine hundred eighty-one thousand, six hundred thirty-four".