1565216551 has 4 divisors (see below), whose sum is σ = 1565418600. Its totient is φ = 1565014504.

The previous prime is 1565216479. The next prime is 1565216663. The reversal of 1565216551 is 1556125651.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1565216551 - 2¹⁵ = 1565183783 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1565216551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1565210551) 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, 88921 + ... + 105058.

It is an arithmetic number, because the mean of its divisors is an integer number (391354650).

Almost surely, 2^1565216551 is an apocalyptic number.

1565216551 is a deficient number, since it is larger than the sum of its proper divisors (202049).

1565216551 is an equidigital number, since it uses as much as digits as its factorization.

1565216551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202048.

The product of its digits is 45000, while the sum is 37.

The square root of 1565216551 is about 39562.8177838738. The cubic root of 1565216551 is about 1161.0693050681.

The spelling of 1565216551 in words is "one billion, five hundred sixty-five million, two hundred sixteen thousand, five hundred fifty-one".