87921990 has 128 divisors (see below), whose sum is σ = 259701120. Its totient is φ = 21026304.

The previous prime is 87921979. The next prime is 87921991. The reversal of 87921990 is 9912978.

It is a super-3 number, since 3×87921990³ (a number of 25 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87921991) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 129532 + ... + 130208.

It is an arithmetic number, because the mean of its divisors is an integer number (2028915).

Almost surely, 2^87921990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 87921990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129850560).

87921990 is an abundant number, since it is smaller than the sum of its proper divisors (171779130).

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

87921990 is a wasteful number, since it uses less digits than its factorization.

87921990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743 (or 737 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 87921990 is about 9376.6726507861. The cubic root of 87921990 is about 444.6645454033.

The spelling of 87921990 in words is "eighty-seven million, nine hundred twenty-one thousand, nine hundred ninety".