21146897491 has 2 divisors, whose sum is σ = 21146897492. Its totient is φ = 21146897490.

The previous prime is 21146897441. The next prime is 21146897537. The reversal of 21146897491 is 19479864112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21146897491 - 2¹⁷ = 21146766419 is a prime.

It is not a weakly prime, because it can be changed into another prime (21146897441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573448745 + 10573448746.

It is an arithmetic number, because the mean of its divisors is an integer number (10573448746).

Almost surely, 2^21146897491 is an apocalyptic number.

21146897491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21146897491 is an equidigital number, since it uses as much as digits as its factorization.

21146897491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 52.

The spelling of 21146897491 in words is "twenty-one billion, one hundred forty-six million, eight hundred ninety-seven thousand, four hundred ninety-one".