21385213906357 has 4 divisors (see below), whose sum is σ = 24440244464416. Its totient is φ = 18330183348300.

The previous prime is 21385213906351. The next prime is 21385213906367. The reversal of 21385213906357 is 75360931258312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21385213906357 - 2¹⁵ = 21385213873589 is a prime.

It is a super-2 number, since 2×21385213906357² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21385213906298 and 21385213906307.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21385213906351) 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, 1527515279019 + ... + 1527515279032.

It is an arithmetic number, because the mean of its divisors is an integer number (6110061116104).

Almost surely, 2^{21385213906357} is an apocalyptic number.

It is an amenable number.

21385213906357 is a deficient number, since it is larger than the sum of its proper divisors (3055030558059).

21385213906357 is an equidigital number, since it uses as much as digits as its factorization.

21385213906357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3055030558058.

The product of its (nonzero) digits is 8164800, while the sum is 55.

The spelling of 21385213906357 in words is "twenty-one trillion, three hundred eighty-five billion, two hundred thirteen million, nine hundred six thousand, three hundred fifty-seven".