210661990 has 64 divisors (see below), whose sum is σ = 482899968. Its totient is φ = 64252800.

The previous prime is 210661961. The next prime is 210661999. The reversal of 210661990 is 99166012.

210661990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210661999) 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, 33280 + ... + 39100.

It is an arithmetic number, because the mean of its divisors is an integer number (7545312).

Almost surely, 2^210661990 is an apocalyptic number.

210661990 is an abundant number, since it is smaller than the sum of its proper divisors (272237978).

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

210661990 is a wasteful number, since it uses less digits than its factorization.

210661990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5893.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 210661990 is about 14514.1995990134. The cubic root of 210661990 is about 595.0161142447.

The spelling of 210661990 in words is "two hundred ten million, six hundred sixty-one thousand, nine hundred ninety".