1661551534 has 4 divisors (see below), whose sum is σ = 2492327304. Its totient is φ = 830775766.

The previous prime is 1661551523. The next prime is 1661551543. The reversal of 1661551534 is 4351551661.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 1661551493 and 1661551502.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 415387882 + ... + 415387885.

It is an arithmetic number, because the mean of its divisors is an integer number (623081826).

Almost surely, 2^1661551534 is an apocalyptic number.

1661551534 is a deficient number, since it is larger than the sum of its proper divisors (830775770).

1661551534 is an equidigital number, since it uses as much as digits as its factorization.

1661551534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 830775769.

The product of its digits is 54000, while the sum is 37.

The square root of 1661551534 is about 40762.1335800765. The cubic root of 1661551534 is about 1184.4169264394.

The spelling of 1661551534 in words is "one billion, six hundred sixty-one million, five hundred fifty-one thousand, five hundred thirty-four".