921750021 has 48 divisors (see below), whose sum is σ = 1456266240. Its totient is φ = 559833120.

The previous prime is 921750019. The next prime is 921750043. The reversal of 921750021 is 120057129.

It is not a de Polignac number, because 921750021 - 2¹ = 921750019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921750121) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 491716 + ... + 493586.

It is an arithmetic number, because the mean of its divisors is an integer number (30338880).

Almost surely, 2^921750021 is an apocalyptic number.

It is an amenable number.

921750021 is a deficient number, since it is larger than the sum of its proper divisors (534516219).

921750021 is a wasteful number, since it uses less digits than its factorization.

921750021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2006 (or 2003 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 921750021 is about 30360.3363123665. The cubic root of 921750021 is about 973.2051207107.

The spelling of 921750021 in words is "nine hundred twenty-one million, seven hundred fifty thousand, twenty-one".