921720159 has 6 divisors (see below), whose sum is σ = 1331373576. Its totient is φ = 614480100.

The previous prime is 921720131. The next prime is 921720167. The reversal of 921720159 is 951027129.

It is not a de Polignac number, because 921720159 - 2⁷ = 921720031 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921720169) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 51206667 + ... + 51206684.

It is an arithmetic number, because the mean of its divisors is an integer number (221895596).

Almost surely, 2^921720159 is an apocalyptic number.

921720159 is a deficient number, since it is larger than the sum of its proper divisors (409653417).

921720159 is a wasteful number, since it uses less digits than its factorization.

921720159 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102413357 (or 102413354 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 36.

The square root of 921720159 is about 30359.8445154121. The cubic root of 921720159 is about 973.1946109324.

The spelling of 921720159 in words is "nine hundred twenty-one million, seven hundred twenty thousand, one hundred fifty-nine".