21510051001 has 2 divisors, whose sum is σ = 21510051002. Its totient is φ = 21510051000.

The previous prime is 21510050977. The next prime is 21510051037. The reversal of 21510051001 is 10015001512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15055535401 + 6454515600 = 122701^2 + 80340^2 .

It is a cyclic number.

It is not a de Polignac number, because 21510051001 - 2¹⁹ = 21509526713 is a prime.

It is a super-2 number, since 2×21510051001² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21510051061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10755025500 + 10755025501.

It is an arithmetic number, because the mean of its divisors is an integer number (10755025501).

Almost surely, 2^21510051001 is an apocalyptic number.

It is an amenable number.

21510051001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21510051001 is an equidigital number, since it uses as much as digits as its factorization.

21510051001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 50, while the sum is 16.

Adding to 21510051001 its reverse (10015001512), we get a palindrome (31525052513).

The spelling of 21510051001 in words is "twenty-one billion, five hundred ten million, fifty-one thousand, one".