1661551533 has 24 divisors (see below), whose sum is σ = 2527806528. Its totient is φ = 1049623872.

The previous prime is 1661551523. The next prime is 1661551543. The reversal of 1661551533 is 3351551661.

1661551533 is a `hidden beast` number, since 1 + 6 + 615 + 5 + 1 + 5 + 33 = 666.

It is an interprime number because it is at equal distance from previous prime (1661551523) and next prime (1661551543).

It is not a de Polignac number, because 1661551533 - 2¹⁴ = 1661535149 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661551513) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15360 + ... + 59657.

It is an arithmetic number, because the mean of its divisors is an integer number (105325272).

Almost surely, 2^1661551533 is an apocalyptic number.

It is an amenable number.

1661551533 is a deficient number, since it is larger than the sum of its proper divisors (866254995).

1661551533 is a wasteful number, since it uses less digits than its factorization.

1661551533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75153 (or 75150 counting only the distinct ones).

The product of its digits is 40500, while the sum is 36.

The square root of 1661551533 is about 40762.1335678102. The cubic root of 1661551533 is about 1184.4169262017.

The spelling of 1661551533 in words is "one billion, six hundred sixty-one million, five hundred fifty-one thousand, five hundred thirty-three".