20440072421 has 2 divisors, whose sum is σ = 20440072422. Its totient is φ = 20440072420.

The previous prime is 20440072337. The next prime is 20440072463. The reversal of 20440072421 is 12427004402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16663969921 + 3776102500 = 129089^2 + 61450^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20440072421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20440072021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10220036210 + 10220036211.

It is an arithmetic number, because the mean of its divisors is an integer number (10220036211).

Almost surely, 2^20440072421 is an apocalyptic number.

It is an amenable number.

20440072421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20440072421 is an equidigital number, since it uses as much as digits as its factorization.

20440072421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3584, while the sum is 26.

Adding to 20440072421 its reverse (12427004402), we get a palindrome (32867076823).

The spelling of 20440072421 in words is "twenty billion, four hundred forty million, seventy-two thousand, four hundred twenty-one".