21185336390821 has 16 divisors (see below), whose sum is σ = 22388506624000. Its totient is φ = 20015129075760.

The previous prime is 21185336390773. The next prime is 21185336390903. The reversal of 21185336390821 is 12809363358112.

It is a cyclic number.

It is not a de Polignac number, because 21185336390821 - 2⁷ = 21185336390693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185336390521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1310565 + ... + 6639898.

It is an arithmetic number, because the mean of its divisors is an integer number (1399281664000).

Almost surely, 2^{21185336390821} is an apocalyptic number.

It is an amenable number.

21185336390821 is a deficient number, since it is larger than the sum of its proper divisors (1203170233179).

21185336390821 is a wasteful number, since it uses less digits than its factorization.

21185336390821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7952536.

The product of its (nonzero) digits is 1866240, while the sum is 52.

The spelling of 21185336390821 in words is "twenty-one trillion, one hundred eighty-five billion, three hundred thirty-six million, three hundred ninety thousand, eight hundred twenty-one".