1561461621 has 8 divisors (see below), whose sum is σ = 2089632384. Its totient is φ = 1037132640.

The previous prime is 1561461613. The next prime is 1561461631. The reversal of 1561461621 is 1261641651.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1561461621 - 2³ = 1561461613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561461631) 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, 959496 + ... + 961121.

It is an arithmetic number, because the mean of its divisors is an integer number (261204048).

Almost surely, 2^1561461621 is an apocalyptic number.

It is an amenable number.

1561461621 is a deficient number, since it is larger than the sum of its proper divisors (528170763).

1561461621 is a wasteful number, since it uses less digits than its factorization.

1561461621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1920891.

The product of its digits is 8640, while the sum is 33.

The square root of 1561461621 is about 39515.3339983354. Note that the first 3 decimals coincide. The cubic root of 1561461621 is about 1160.1400992599.

The spelling of 1561461621 in words is "one billion, five hundred sixty-one million, four hundred sixty-one thousand, six hundred twenty-one".