1561761002 has 4 divisors (see below), whose sum is σ = 2342641506. Its totient is φ = 780880500.

The previous prime is 1561761001. The next prime is 1561761011. The reversal of 1561761002 is 2001671651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 2001671651 = 7 ⋅285953093.

It can be written as a sum of positive squares in only one way, i.e., 1518582961 + 43178041 = 38969^2 + 6571^2 .

It is not an unprimeable number, because it can be changed into a prime (1561761001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390440249 + ... + 390440252.

Almost surely, 2^1561761002 is an apocalyptic number.

1561761002 is a deficient number, since it is larger than the sum of its proper divisors (780880504).

1561761002 is an equidigital number, since it uses as much as digits as its factorization.

1561761002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 780880503.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 1561761002 is about 39519.1219791128. The cubic root of 1561761002 is about 1160.2142395618.

The spelling of 1561761002 in words is "one billion, five hundred sixty-one million, seven hundred sixty-one thousand, two".