29638721281 has 81 divisors (see below), whose sum is σ = 36880747803. Its totient is φ = 23799260160.

The previous prime is 29638721263. The next prime is 29638721293. The reversal of 29638721281 is 18212783692.

The square root of 29638721281 is 172159.

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

It can be written as a sum of positive squares in 13 ways, for example, as 29169565681 + 469155600 = 170791^2 + 21660^2 .

It is not a de Polignac number, because 29638721281 - 2⁵ = 29638721249 is a prime.

It is a super-2 number, since 2×29638721281² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (29638721261) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 722895621 + ... + 722895661.

Almost surely, 2^29638721281 is an apocalyptic number.

29638721281 is the 172159-th square number.

29638721281 is the 86080-th centered octagonal number.

It is an amenable number.

29638721281 is a deficient number, since it is larger than the sum of its proper divisors (7242026522).

29638721281 is a wasteful number, since it uses less digits than its factorization.

29638721281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 90 counting only the distinct ones).

The product of its digits is 580608, while the sum is 49.

Multiplying 29638721281 by its sum of digits (49), we get a square (1452297342769 = 1205113²).

The spelling of 29638721281 in words is "twenty-nine billion, six hundred thirty-eight million, seven hundred twenty-one thousand, two hundred eighty-one".