21261264499 has 16 divisors (see below), whose sum is σ = 22567438080. Its totient is φ = 19974034080.

The previous prime is 21261264491. The next prime is 21261264529. The reversal of 21261264499 is 99446216212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21261264499 - 2³ = 21261264491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21261264491) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5192497 + ... + 5196589.

It is an arithmetic number, because the mean of its divisors is an integer number (1410464880).

Almost surely, 2^21261264499 is an apocalyptic number.

21261264499 is a deficient number, since it is larger than the sum of its proper divisors (1306173581).

21261264499 is a wasteful number, since it uses less digits than its factorization.

21261264499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6330.

The product of its digits is 373248, while the sum is 46.

The spelling of 21261264499 in words is "twenty-one billion, two hundred sixty-one million, two hundred sixty-four thousand, four hundred ninety-nine".