21920455917 has 24 divisors (see below), whose sum is σ = 32006484120. Its totient is φ = 14455324800.

The previous prime is 21920455903. The next prime is 21920455919. The reversal of 21920455917 is 71955402912.

21920455917 is a `hidden beast` number, since 2 + 1 + 92 + 0 + 4 + 559 + 1 + 7 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 3105944361 + 18814511556 = 55731^2 + 137166^2 .

It is not a de Polignac number, because 21920455917 - 2⁴ = 21920455901 is a prime.

It is a super-3 number, since 3×21920455917³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21920455919) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1004559 + ... + 1026147.

It is an arithmetic number, because the mean of its divisors is an integer number (1333603505).

Almost surely, 2^21920455917 is an apocalyptic number.

It is an amenable number.

21920455917 is a deficient number, since it is larger than the sum of its proper divisors (10086028203).

21920455917 is a wasteful number, since it uses less digits than its factorization.

21920455917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22813 (or 22810 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 45.

The spelling of 21920455917 in words is "twenty-one billion, nine hundred twenty million, four hundred fifty-five thousand, nine hundred seventeen".