21920985405 has 96 divisors (see below), whose sum is σ = 42685014528. Its totient is φ = 10313395200.

The previous prime is 21920985397. The next prime is 21920985433. The reversal of 21920985405 is 50458902912.

It is a happy number.

21920985405 is a `hidden beast` number, since 2 + 19 + 2 + 0 + 98 + 540 + 5 = 666.

It is not a de Polignac number, because 21920985405 - 2³ = 21920985397 is a prime.

It is a super-2 number, since 2×21920985405² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7892377 + ... + 7895153.

It is an arithmetic number, because the mean of its divisors is an integer number (444635568).

Almost surely, 2^21920985405 is an apocalyptic number.

It is an amenable number.

21920985405 is a deficient number, since it is larger than the sum of its proper divisors (20764029123).

21920985405 is a wasteful number, since it uses less digits than its factorization.

21920985405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3267 (or 3264 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The spelling of 21920985405 in words is "twenty-one billion, nine hundred twenty million, nine hundred eighty-five thousand, four hundred five".