21261262651 has 8 divisors (see below), whose sum is σ = 21485790000. Its totient is φ = 21037010400.

The previous prime is 21261262609. The next prime is 21261262657. The reversal of 21261262651 is 15626216212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21261262651 - 2¹⁷ = 21261131579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21261262657) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88500 + ... + 224398.

It is an arithmetic number, because the mean of its divisors is an integer number (2685723750).

Almost surely, 2^21261262651 is an apocalyptic number.

21261262651 is a deficient number, since it is larger than the sum of its proper divisors (224527349).

21261262651 is a wasteful number, since it uses less digits than its factorization.

21261262651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137549.

The product of its digits is 17280, while the sum is 34.

Adding to 21261262651 its reverse (15626216212), we get a palindrome (36887478863).

The spelling of 21261262651 in words is "twenty-one billion, two hundred sixty-one million, two hundred sixty-two thousand, six hundred fifty-one".