1561372775 has 12 divisors (see below), whose sum is σ = 1967843544. Its totient is φ = 1228620000.

The previous prime is 1561372763. The next prime is 1561372793. The reversal of 1561372775 is 5772731651.

It is not a de Polignac number, because 1561372775 - 2⁶ = 1561372711 is a prime.

It is a super-2 number, since 2×1561372775² = 4875769885022401250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 510401 + ... + 513450.

It is an arithmetic number, because the mean of its divisors is an integer number (163986962).

Almost surely, 2^1561372775 is an apocalyptic number.

1561372775 is a deficient number, since it is larger than the sum of its proper divisors (406470769).

1561372775 is a wasteful number, since it uses less digits than its factorization.

1561372775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1023922 (or 1023917 counting only the distinct ones).

The product of its digits is 308700, while the sum is 44.

The square root of 1561372775 is about 39514.2097858479. The cubic root of 1561372775 is about 1160.1180951409.

It can be divided in two parts, 15613 and 72775, that added together give a palindrome (88388).

The spelling of 1561372775 in words is "one billion, five hundred sixty-one million, three hundred seventy-two thousand, seven hundred seventy-five".