8121990 has 64 divisors (see below), whose sum is σ = 20736000. Its totient is φ = 2031744.

The previous prime is 8121983. The next prime is 8121991. The reversal of 8121990 is 991218.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8121991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54436 + ... + 54584.

It is an arithmetic number, because the mean of its divisors is an integer number (324000).

Almost surely, 2^8121990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8121990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10368000).

8121990 is an abundant number, since it is smaller than the sum of its proper divisors (12614010).

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

8121990 is a wasteful number, since it uses less digits than its factorization.

8121990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 8121990 is about 2849.9105249113. The cubic root of 8121990 is about 201.0114594590.

The spelling of 8121990 in words is "eight million, one hundred twenty-one thousand, nine hundred ninety".