21177695297929 has 27 divisors (see below), whose sum is σ = 22194799008213. Its totient is φ = 20206344400704.

The previous prime is 21177695297921. The next prime is 21177695297977. The reversal of 21177695297929 is 92979259677112.

The square root of 21177695297929 is 4601923.

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 1939120305529 + 19238574992400 = 1392523^2 + 4386180^2 .

It is not a de Polignac number, because 21177695297929 - 2³ = 21177695297921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21177695297921) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11877562372 + ... + 11877564154.

Almost surely, 2^{21177695297929} is an apocalyptic number.

21177695297929 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21177695297929 is the 4601923-rd square number.

21177695297929 is the 2300962-nd centered octagonal number.

It is an amenable number.

21177695297929 is a deficient number, since it is larger than the sum of its proper divisors (1017103710284).

21177695297929 is an frugal number, since it uses more digits than its factorization.

21177695297929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3802 (or 1901 counting only the distinct ones).

The product of its digits is 540101520, while the sum is 76.

The spelling of 21177695297929 in words is "twenty-one trillion, one hundred seventy-seven billion, six hundred ninety-five million, two hundred ninety-seven thousand, nine hundred twenty-nine".