21401032421 has 2 divisors, whose sum is σ = 21401032422. Its totient is φ = 21401032420.

The previous prime is 21401032319. The next prime is 21401032427. The reversal of 21401032421 is 12423010412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19559421025 + 1841611396 = 139855^2 + 42914^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21401032421 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21401032393 and 21401032402.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21401032427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700516210 + 10700516211.

It is an arithmetic number, because the mean of its divisors is an integer number (10700516211).

Almost surely, 2^21401032421 is an apocalyptic number.

It is an amenable number.

21401032421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21401032421 is an equidigital number, since it uses as much as digits as its factorization.

21401032421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21401032421 its reverse (12423010412), we get a palindrome (33824042833).

The spelling of 21401032421 in words is "twenty-one billion, four hundred one million, thirty-two thousand, four hundred twenty-one".