21006733969 has 9 divisors (see below), whose sum is σ = 22748977233. Its totient is φ = 19389092112.

The previous prime is 21006733939. The next prime is 21006733997. The reversal of 21006733969 is 96933760012.

The square root of 21006733969 is 144937.

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

It can be written as a sum of positive squares in 4 ways, for example, as 6537531025 + 14469202944 = 80855^2 + 120288^2 .

It is not a de Polignac number, because 21006733969 - 2⁷ = 21006733841 is a prime.

It is a super-2 number, since 2×21006733969² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21006733939) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1878607 + ... + 1889755.

It is an arithmetic number, because the mean of its divisors is an integer number (2527664137).

Almost surely, 2^21006733969 is an apocalyptic number.

21006733969 is the 144937-th square number.

21006733969 is the 72469-th centered octagonal number.

It is an amenable number.

21006733969 is a deficient number, since it is larger than the sum of its proper divisors (1742243264).

21006733969 is an frugal number, since it uses more digits than its factorization.

21006733969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22324 (or 11162 counting only the distinct ones).

The product of its (nonzero) digits is 367416, while the sum is 46.

It can be divided in two parts, 210067 and 33969, that added together give a square (244036 = 494²).

The spelling of 21006733969 in words is "twenty-one billion, six million, seven hundred thirty-three thousand, nine hundred sixty-nine".