21000102421 has 2 divisors, whose sum is σ = 21000102422. Its totient is φ = 21000102420.

The previous prime is 21000102407. The next prime is 21000102433. The reversal of 21000102421 is 12420100012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20941273521 + 58828900 = 144711^2 + 7670^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000102421 - 2²⁷ = 20865884693 is a prime.

It is a super-2 number, since 2×21000102421² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000102121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500051210 + 10500051211.

It is an arithmetic number, because the mean of its divisors is an integer number (10500051211).

Almost surely, 2^21000102421 is an apocalyptic number.

It is an amenable number.

21000102421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000102421 is an equidigital number, since it uses as much as digits as its factorization.

21000102421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21000102421 its reverse (12420100012), we get a palindrome (33420202433).

The spelling of 21000102421 in words is "twenty-one billion, one hundred two thousand, four hundred twenty-one".