921255981 has 4 divisors (see below), whose sum is σ = 1228341312. Its totient is φ = 614170652.

The previous prime is 921255953. The next prime is 921255991. The reversal of 921255981 is 189552129.

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.

It is a cyclic number.

It is not a de Polignac number, because 921255981 - 2⁶ = 921255917 is a prime.

It is a super-2 number, since 2×921255981² = 1697425165056544722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921255991) 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, 153542661 + ... + 153542666.

It is an arithmetic number, because the mean of its divisors is an integer number (307085328).

Almost surely, 2^921255981 is an apocalyptic number.

It is an amenable number.

921255981 is a deficient number, since it is larger than the sum of its proper divisors (307085331).

921255981 is a wasteful number, since it uses less digits than its factorization.

921255981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 307085330.

The product of its digits is 64800, while the sum is 42.

The square root of 921255981 is about 30352.1989483464. The cubic root of 921255981 is about 973.0312166612.

The spelling of 921255981 in words is "nine hundred twenty-one million, two hundred fifty-five thousand, nine hundred eighty-one".