21240854781 has 16 divisors (see below), whose sum is σ = 29030802240. Its totient is φ = 13806898560.

The previous prime is 21240854777. The next prime is 21240854783. The reversal of 21240854781 is 18745804212.

It is not a de Polignac number, because 21240854781 - 2² = 21240854777 is a prime.

It is a super-2 number, since 2×21240854781² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240854783) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 71290 + ... + 218091.

It is an arithmetic number, because the mean of its divisors is an integer number (1814425140).

Almost surely, 2^21240854781 is an apocalyptic number.

It is an amenable number.

21240854781 is a deficient number, since it is larger than the sum of its proper divisors (7789947459).

21240854781 is a wasteful number, since it uses less digits than its factorization.

21240854781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289996.

The product of its (nonzero) digits is 143360, while the sum is 42.

The spelling of 21240854781 in words is "twenty-one billion, two hundred forty million, eight hundred fifty-four thousand, seven hundred eighty-one".