1561720 has 16 divisors (see below), whose sum is σ = 3513960. Its totient is φ = 624672.

The previous prime is 1561711. The next prime is 1561727. The reversal of 1561720 is 271651.

It is a junction number, because it is equal to n+sod(n) for n = 1561691 and 1561700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19482 + ... + 19561.

2^1561720 is an apocalyptic number.

1561720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561720 is an abundant number, since it is smaller than the sum of its proper divisors (1952240).

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

1561720 is a wasteful number, since it uses less digits than its factorization.

1561720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39054 (or 39050 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 1561720 is about 1249.6879610527. The cubic root of 1561720 is about 116.0204086169.

The spelling of 1561720 in words is "one million, five hundred sixty-one thousand, seven hundred twenty".