21018400705 has 16 divisors (see below), whose sum is σ = 25786024704. Its totient is φ = 16439516800.

The previous prime is 21018400639. The next prime is 21018400727. The reversal of 21018400705 is 50700481012.

It is not a de Polignac number, because 21018400705 - 2⁷ = 21018400577 is a prime.

It is a super-3 number, since 3×21018400705³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 177030 + ... + 270880.

It is an arithmetic number, because the mean of its divisors is an integer number (1611626544).

Almost surely, 2^21018400705 is an apocalyptic number.

It is an amenable number.

21018400705 is a deficient number, since it is larger than the sum of its proper divisors (4767623999).

21018400705 is an equidigital number, since it uses as much as digits as its factorization.

21018400705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94856.

The product of its (nonzero) digits is 2240, while the sum is 28.

Adding to 21018400705 its reverse (50700481012), we get a palindrome (71718881717).

The spelling of 21018400705 in words is "twenty-one billion, eighteen million, four hundred thousand, seven hundred five".