126999821506 has 4 divisors (see below), whose sum is σ = 190499732262. Its totient is φ = 63499910752.

The previous prime is 126999821479. The next prime is 126999821513. The reversal of 126999821506 is 605128999621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 605128999621 = 142183 ⋅4255987.

It can be written as a sum of positive squares in only one way, i.e., 120819503281 + 6180318225 = 347591^2 + 78615^2 .

It is a super-2 number, since 2×126999821506² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31749955375 + ... + 31749955378.

Almost surely, 2^126999821506 is an apocalyptic number.

126999821506 is a deficient number, since it is larger than the sum of its proper divisors (63499910756).

126999821506 is an equidigital number, since it uses as much as digits as its factorization.

126999821506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63499910755.

The product of its (nonzero) digits is 4199040, while the sum is 58.

The spelling of 126999821506 in words is "one hundred twenty-six billion, nine hundred ninety-nine million, eight hundred twenty-one thousand, five hundred six".