1821391506826 has 16 divisors (see below), whose sum is σ = 2767768698240. Its totient is φ = 898811091360.

The previous prime is 1821391506793. The next prime is 1821391506827. The reversal of 1821391506826 is 6286051931281.

It is a happy number.

It is a super-2 number, since 2×1821391506826² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1821391506827) 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, 1888036 + ... + 2684671.

It is an arithmetic number, because the mean of its divisors is an integer number (172985543640).

Almost surely, 2^{1821391506826} is an apocalyptic number.

1821391506826 is a deficient number, since it is larger than the sum of its proper divisors (946377191414).

1821391506826 is a wasteful number, since it uses less digits than its factorization.

1821391506826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4575309.

The product of its (nonzero) digits is 1244160, while the sum is 52.

The spelling of 1821391506826 in words is "one trillion, eight hundred twenty-one billion, three hundred ninety-one million, five hundred six thousand, eight hundred twenty-six".