29811820921 has 9 divisors (see below), whose sum is σ = 31168494021. Its totient is φ = 28511856252.

The previous prime is 29811820889. The next prime is 29811820931. The reversal of 29811820921 is 12902811892.

The square root of 29811820921 is 172661.

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

It is not a de Polignac number, because 29811820921 - 2⁵ = 29811820889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (29811820931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3967450 + ... + 3974956.

Almost surely, 2^29811820921 is an apocalyptic number.

29811820921 is the 172661-st square number.

29811820921 is the 86331-st centered octagonal number.

It is an amenable number.

29811820921 is a deficient number, since it is larger than the sum of its proper divisors (1356673100).

29811820921 is an frugal number, since it uses more digits than its factorization.

29811820921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15060 (or 7530 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 43.

The spelling of 29811820921 in words is "twenty-nine billion, eight hundred eleven million, eight hundred twenty thousand, nine hundred twenty-one".