21445304251 has 16 divisors (see below), whose sum is σ = 24657834240. Its totient is φ = 18270105120.

The previous prime is 21445304249. The next prime is 21445304263. The reversal of 21445304251 is 15240354412.

It is a cyclic number.

It is not a de Polignac number, because 21445304251 - 2¹ = 21445304249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21445304281) 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, 4622505 + ... + 4627141.

It is an arithmetic number, because the mean of its divisors is an integer number (1541114640).

Almost surely, 2^21445304251 is an apocalyptic number.

21445304251 is a deficient number, since it is larger than the sum of its proper divisors (3212529989).

21445304251 is a wasteful number, since it uses less digits than its factorization.

21445304251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8514.

The product of its (nonzero) digits is 19200, while the sum is 31.

Adding to 21445304251 its reverse (15240354412), we get a palindrome (36685658663).

The spelling of 21445304251 in words is "twenty-one billion, four hundred forty-five million, three hundred four thousand, two hundred fifty-one".