21487100491 has 2 divisors, whose sum is σ = 21487100492. Its totient is φ = 21487100490.

The previous prime is 21487100441. The next prime is 21487100519. The reversal of 21487100491 is 19400178412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21487100491 - 2¹³ = 21487092299 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21487100491.

It is not a weakly prime, because it can be changed into another prime (21487100441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10743550245 + 10743550246.

It is an arithmetic number, because the mean of its divisors is an integer number (10743550246).

Almost surely, 2^21487100491 is an apocalyptic number.

21487100491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21487100491 is an equidigital number, since it uses as much as digits as its factorization.

21487100491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The spelling of 21487100491 in words is "twenty-one billion, four hundred eighty-seven million, one hundred thousand, four hundred ninety-one".