21651945316 has 81 divisors (see below), whose sum is σ = 40868879961. Its totient is φ = 10036534368.

The previous prime is 21651945277. The next prime is 21651945317. The reversal of 21651945316 is 61354915612.

The square root of 21651945316 is 147146.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 11353754916 + 10298190400 = 106554^2 + 101480^2 .

It is a super-3 number, since 3×21651945316³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21651945317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 366982095 + ... + 366982153.

Almost surely, 2^21651945316 is an apocalyptic number.

21651945316 is the 147146-th square number.

It is an amenable number.

21651945316 is a deficient number, since it is larger than the sum of its proper divisors (19216934645).

21651945316 is an equidigital number, since it uses as much as digits as its factorization.

21651945316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266 (or 133 counting only the distinct ones).

The product of its digits is 194400, while the sum is 43.

The spelling of 21651945316 in words is "twenty-one billion, six hundred fifty-one million, nine hundred forty-five thousand, three hundred sixteen".