21890821025851 has 4 divisors (see below), whose sum is σ = 21890839063104. Its totient is φ = 21890802988600.

The previous prime is 21890821025849. The next prime is 21890821025921. The reversal of 21890821025851 is 15852012809812.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21890821025851 - 2¹ = 21890821025849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21890821065851) 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, 7055755 + ... + 9672916.

It is an arithmetic number, because the mean of its divisors is an integer number (5472709765776).

Almost surely, 2^{21890821025851} is an apocalyptic number.

21890821025851 is a deficient number, since it is larger than the sum of its proper divisors (18037253).

21890821025851 is a wasteful number, since it uses less digits than its factorization.

21890821025851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18037252.

The product of its (nonzero) digits is 921600, while the sum is 52.

The spelling of 21890821025851 in words is "twenty-one trillion, eight hundred ninety billion, eight hundred twenty-one million, twenty-five thousand, eight hundred fifty-one".