1661491590 has 64 divisors (see below), whose sum is σ = 4411418112. Its totient is φ = 397107200.

The previous prime is 1661491571. The next prime is 1661491621. The reversal of 1661491590 is 951941661.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12027 + ... + 58886.

It is an arithmetic number, because the mean of its divisors is an integer number (68928408).

Almost surely, 2^1661491590 is an apocalyptic number.

1661491590 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1661491590 is an abundant number, since it is smaller than the sum of its proper divisors (2749926522).

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

1661491590 is a wasteful number, since it uses less digits than its factorization.

1661491590 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71005.

The product of its (nonzero) digits is 58320, while the sum is 42.

The square root of 1661491590 is about 40761.3982831796. The cubic root of 1661491590 is about 1184.4026828161.

The spelling of 1661491590 in words is "one billion, six hundred sixty-one million, four hundred ninety-one thousand, five hundred ninety".