90451561 has 4 divisors (see below), whose sum is σ = 90470800. Its totient is φ = 90432324.

The previous prime is 90451523. The next prime is 90451589. The reversal of 90451561 is 16515409.

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 an emirpimes, since its reverse is a distinct semiprime: 16515409 = 421 ⋅39229.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-90451561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90451511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2650 + ... + 13708.

It is an arithmetic number, because the mean of its divisors is an integer number (22617700).

Almost surely, 2^90451561 is an apocalyptic number.

It is an amenable number.

90451561 is a deficient number, since it is larger than the sum of its proper divisors (19239).

90451561 is a wasteful number, since it uses less digits than its factorization.

90451561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19238.

The product of its (nonzero) digits is 5400, while the sum is 31.

The square root of 90451561 is about 9510.6025571464. The cubic root of 90451561 is about 448.8887163590. Note that the first 3 decimals are identical.

The spelling of 90451561 in words is "ninety million, four hundred fifty-one thousand, five hundred sixty-one".