21905753523021 has 6 divisors (see below), whose sum is σ = 31641643977710. Its totient is φ = 14603835682008.

The previous prime is 21905753523019. The next prime is 21905753523023. The reversal of 21905753523021 is 12032535750912.

21905753523021 is a `hidden beast` number, since 2 + 1 + 9 + 0 + 57 + 53 + 523 + 0 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (21905753523019) and next prime (21905753523023).

It can be written as a sum of positive squares in only one way, i.e., 12742479654921 + 9163273868100 = 3569661^2 + 3027090^2 .

It is not a de Polignac number, because 21905753523021 - 2¹ = 21905753523019 is a prime.

It is a super-2 number, since 2×21905753523021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21905753523023) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1216986306826 + ... + 1216986306843.

Almost surely, 2^{21905753523021} is an apocalyptic number.

It is an amenable number.

21905753523021 is a deficient number, since it is larger than the sum of its proper divisors (9735890454689).

21905753523021 is a wasteful number, since it uses less digits than its factorization.

21905753523021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2433972613675 (or 2433972613672 counting only the distinct ones).

The product of its (nonzero) digits is 567000, while the sum is 45.

The spelling of 21905753523021 in words is "twenty-one trillion, nine hundred five billion, seven hundred fifty-three million, five hundred twenty-three thousand, twenty-one".