It is a happy number.
It is an unprimeable number.
22151660 is an apocalyptic number.
2151660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 2151660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3548160).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
2151660 is a wasteful number, since it uses less digits than its factorization.
2151660 is an evil number, because the sum of its binary digits is even.
The square root of 2151660 is about 1466.8537759436. The cubic root of 2151660 is about 129.0994965824.
The spelling of 2151660 in words is "two million, one hundred fifty-one thousand, six hundred sixty".