1951527661 has 4 divisors (see below), whose sum is σ = 1951617472. Its totient is φ = 1951437852.

The previous prime is 1951527637. The next prime is 1951527703. The reversal of 1951527661 is 1667251591.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1667251591 = 17 ⋅98073623.

It is a cyclic number.

It is not a de Polignac number, because 1951527661 - 2⁵ = 1951527629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1951521661) 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, 10366 + ... + 63328.

It is an arithmetic number, because the mean of its divisors is an integer number (487904368).

Almost surely, 2^1951527661 is an apocalyptic number.

It is an amenable number.

1951527661 is a deficient number, since it is larger than the sum of its proper divisors (89811).

1951527661 is an equidigital number, since it uses as much as digits as its factorization.

1951527661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89810.

The product of its digits is 113400, while the sum is 43.

The square root of 1951527661 is about 44176.0982998725. The cubic root of 1951527661 is about 1249.6591414075.

The spelling of 1951527661 in words is "one billion, nine hundred fifty-one million, five hundred twenty-seven thousand, six hundred sixty-one".