21621007305 has 12 divisors (see below), whose sum is σ = 37476412740. Its totient is φ = 11531203872.

The previous prime is 21621007253. The next prime is 21621007321. The reversal of 21621007305 is 50370012612.

It is a happy number.

21621007305 is a `hidden beast` number, since 2 + 1 + 621 + 0 + 0 + 7 + 30 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 14308705161 + 7312302144 = 119619^2 + 85512^2 .

It is not a de Polignac number, because 21621007305 - 2⁸ = 21621007049 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 240233370 + ... + 240233459.

It is an arithmetic number, because the mean of its divisors is an integer number (3123034395).

Almost surely, 2^21621007305 is an apocalyptic number.

It is an amenable number.

21621007305 is a deficient number, since it is larger than the sum of its proper divisors (15855405435).

21621007305 is a wasteful number, since it uses less digits than its factorization.

21621007305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 480466840 (or 480466837 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

Adding to 21621007305 its reverse (50370012612), we get a palindrome (71991019917).

The spelling of 21621007305 in words is "twenty-one billion, six hundred twenty-one million, seven thousand, three hundred five".