21507790673896 has 16 divisors (see below), whose sum is σ = 42699290308740. Its totient is φ = 10121313258240.

The previous prime is 21507790673893. The next prime is 21507790673939. The reversal of 21507790673896 is 69837609770512.

It can be written as a sum of positive squares in 2 ways, for example, as 21507055504900 + 735168996 = 4637570^2 + 27114^2 .

It is not an unprimeable number, because it can be changed into a prime (21507790673893) 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, 79072759695 + ... + 79072759966.

Almost surely, 2^{21507790673896} is an apocalyptic number.

It is an amenable number.

21507790673896 is a deficient number, since it is larger than the sum of its proper divisors (21191499634844).

21507790673896 is a wasteful number, since it uses less digits than its factorization.

21507790673896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158145519684 (or 158145519680 counting only the distinct ones).

The product of its (nonzero) digits is 240045120, while the sum is 70.

The spelling of 21507790673896 in words is "twenty-one trillion, five hundred seven billion, seven hundred ninety million, six hundred seventy-three thousand, eight hundred ninety-six".