921717421 has 4 divisors (see below), whose sum is σ = 921778144. Its totient is φ = 921656700.

The previous prime is 921717413. The next prime is 921717437. The reversal of 921717421 is 124717129.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 921717421 - 2³ = 921717413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921717481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14776 + ... + 45406.

It is an arithmetic number, because the mean of its divisors is an integer number (230444536).

Almost surely, 2^921717421 is an apocalyptic number.

It is an amenable number.

921717421 is a deficient number, since it is larger than the sum of its proper divisors (60723).

921717421 is a wasteful number, since it uses less digits than its factorization.

921717421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60722.

The product of its digits is 7056, while the sum is 34.

The square root of 921717421 is about 30359.7994229211. The cubic root of 921717421 is about 973.1936472959.

The spelling of 921717421 in words is "nine hundred twenty-one million, seven hundred seventeen thousand, four hundred twenty-one".