21242450491 has 4 divisors (see below), whose sum is σ = 21481129800. Its totient is φ = 21003771184.

The previous prime is 21242450477. The next prime is 21242450501. The reversal of 21242450491 is 19405424212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21242450491 - 2¹¹ = 21242448443 is a prime.

It is a super-2 number, since 2×21242450491² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21242450401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119339521 + ... + 119339698.

It is an arithmetic number, because the mean of its divisors is an integer number (5370282450).

Almost surely, 2^21242450491 is an apocalyptic number.

21242450491 is a deficient number, since it is larger than the sum of its proper divisors (238679309).

21242450491 is an equidigital number, since it uses as much as digits as its factorization.

21242450491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238679308.

The product of its (nonzero) digits is 23040, while the sum is 34.

The spelling of 21242450491 in words is "twenty-one billion, two hundred forty-two million, four hundred fifty thousand, four hundred ninety-one".