65521566 has 24 divisors (see below), whose sum is σ = 154869624. Its totient is φ = 19854960.

The previous prime is 65521559. The next prime is 65521571. The reversal of 65521566 is 66512556.

It is a happy number.

It is a super-2 number, since 2×65521566² = 8586151222184712, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 65521566.

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, 165261 + ... + 165656.

It is an arithmetic number, because the mean of its divisors is an integer number (6452901).

Almost surely, 2^65521566 is an apocalyptic number.

65521566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

65521566 is an abundant number, since it is smaller than the sum of its proper divisors (89348058).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

65521566 is a wasteful number, since it uses less digits than its factorization.

65521566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330936 (or 330933 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The square root of 65521566 is about 8094.5392703970. The cubic root of 65521566 is about 403.1451346713.

It can be divided in two parts, 6552 and 1566, that added together give a palindrome (8118).

The spelling of 65521566 in words is "sixty-five million, five hundred twenty-one thousand, five hundred sixty-six".