21451504738 has 8 divisors (see below), whose sum is σ = 32178030300. Its totient is φ = 10725494640.

The previous prime is 21451504733. The next prime is 21451504741. The reversal of 21451504738 is 83740515412.

It can be written as a sum of positive squares in 2 ways, for example, as 16288651129 + 5162853609 = 127627^2 + 71853^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21451504738.

It is not an unprimeable number, because it can be changed into a prime (21451504733) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1588 + ... + 207136.

Almost surely, 2^21451504738 is an apocalyptic number.

21451504738 is a deficient number, since it is larger than the sum of its proper divisors (10726525562).

21451504738 is a wasteful number, since it uses less digits than its factorization.

21451504738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257732.

The product of its (nonzero) digits is 134400, while the sum is 40.

The spelling of 21451504738 in words is "twenty-one billion, four hundred fifty-one million, five hundred four thousand, seven hundred thirty-eight".