21523659751 has 16 divisors (see below), whose sum is σ = 24412082688. Its totient is φ = 18804772800.

The previous prime is 21523659749. The next prime is 21523659757. The reversal of 21523659751 is 15795632512.

It is not a de Polignac number, because 21523659751 - 2¹ = 21523659749 is a prime.

It is a super-4 number, since 4×21523659751⁴ (a number of 42 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523659757) 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, 325935 + ... + 386368.

It is an arithmetic number, because the mean of its divisors is an integer number (1525755168).

Almost surely, 2^21523659751 is an apocalyptic number.

21523659751 is a deficient number, since it is larger than the sum of its proper divisors (2888422937).

21523659751 is a wasteful number, since it uses less digits than its factorization.

21523659751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712422.

The product of its digits is 567000, while the sum is 46.

The spelling of 21523659751 in words is "twenty-one billion, five hundred twenty-three million, six hundred fifty-nine thousand, seven hundred fifty-one".