21440234477 has 4 divisors (see below), whose sum is σ = 22131854976. Its totient is φ = 20748613980.

The previous prime is 21440234423. The next prime is 21440234537. The reversal of 21440234477 is 77443204412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21440234477 - 2²⁴ = 21423457261 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21440234477.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440234407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 345810203 + ... + 345810264.

It is an arithmetic number, because the mean of its divisors is an integer number (5532963744).

Almost surely, 2^21440234477 is an apocalyptic number.

It is an amenable number.

21440234477 is a deficient number, since it is larger than the sum of its proper divisors (691620499).

21440234477 is an equidigital number, since it uses as much as digits as its factorization.

21440234477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691620498.

The product of its (nonzero) digits is 150528, while the sum is 38.

Adding to 21440234477 its reverse (77443204412), we get a palindrome (98883438889).

The spelling of 21440234477 in words is "twenty-one billion, four hundred forty million, two hundred thirty-four thousand, four hundred seventy-seven".