921690 has 144 divisors (see below), whose sum is σ = 3201120. Its totient is φ = 181440.

The previous prime is 921677. The next prime is 921703. The reversal of 921690 is 96129.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (921677) and next prime (921703).

It is a super-2 number, since 2×921690² = 1699024912200, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 921690.

It is an unprimeable number.

921690 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 48501 + ... + 48519.

It is an arithmetic number, because the mean of its divisors is an integer number (22230).

2⁹²¹⁶⁹⁰ is an apocalyptic number.

921690 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 921690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1600560).

921690 is an abundant number, since it is smaller than the sum of its proper divisors (2279430).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

921690 is a wasteful number, since it uses less digits than its factorization.

921690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 921690 is about 960.0468738556. The cubic root of 921690 is about 97.3183996396.

The spelling of 921690 in words is "nine hundred twenty-one thousand, six hundred ninety".