261219990 has 16 divisors (see below), whose sum is σ = 626928048. Its totient is φ = 69658656.

The previous prime is 261219989. The next prime is 261219997. The reversal of 261219990 is 99912162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261219997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4353637 + ... + 4353696.

It is an arithmetic number, because the mean of its divisors is an integer number (39183003).

Almost surely, 2^261219990 is an apocalyptic number.

261219990 is an abundant number, since it is smaller than the sum of its proper divisors (365708058).

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

261219990 is a wasteful number, since it uses less digits than its factorization.

261219990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8707343.

The product of its (nonzero) digits is 17496, while the sum is 39.

The square root of 261219990 is about 16162.3015069018. The cubic root of 261219990 is about 639.2471534938.

The spelling of 261219990 in words is "two hundred sixty-one million, two hundred nineteen thousand, nine hundred ninety".