921557431 has 4 divisors (see below), whose sum is σ = 930681864. Its totient is φ = 912433000.

The previous prime is 921557423. The next prime is 921557473. The reversal of 921557431 is 134755129.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 921557431 - 2³ = 921557423 is a prime.

It is a super-2 number, since 2×921557431² = 1698536197262639522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921587431) 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, 4562065 + ... + 4562266.

It is an arithmetic number, because the mean of its divisors is an integer number (232670466).

Almost surely, 2^921557431 is an apocalyptic number.

921557431 is a deficient number, since it is larger than the sum of its proper divisors (9124433).

921557431 is a wasteful number, since it uses less digits than its factorization.

921557431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9124432.

The product of its digits is 37800, while the sum is 37.

The square root of 921557431 is about 30357.1644097402. The cubic root of 921557431 is about 973.1373356550.

The spelling of 921557431 in words is "nine hundred twenty-one million, five hundred fifty-seven thousand, four hundred thirty-one".