21440442721 has 32 divisors (see below), whose sum is σ = 23605464960. Its totient is φ = 19393081344.

The previous prime is 21440442713. The next prime is 21440442733. The reversal of 21440442721 is 12724404412.

It is a cyclic number.

It is not a de Polignac number, because 21440442721 - 2³ = 21440442713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21440442781) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18990085 + ... + 18991213.

It is an arithmetic number, because the mean of its divisors is an integer number (737670780).

Almost surely, 2^21440442721 is an apocalyptic number.

It is an amenable number.

21440442721 is a deficient number, since it is larger than the sum of its proper divisors (2165022239).

21440442721 is a wasteful number, since it uses less digits than its factorization.

21440442721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1585.

The product of its (nonzero) digits is 14336, while the sum is 31.

The spelling of 21440442721 in words is "twenty-one billion, four hundred forty million, four hundred forty-two thousand, seven hundred twenty-one".