90400978 has 4 divisors (see below), whose sum is σ = 135601470. Its totient is φ = 45200488.

The previous prime is 90400969. The next prime is 90400979. The reversal of 90400978 is 87900409.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 85618009 + 4782969 = 9253^2 + 2187^2 .

It is not an unprimeable number, because it can be changed into a prime (90400979) 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 as a sum of consecutive naturals, namely, 22600243 + ... + 22600246.

Almost surely, 2^90400978 is an apocalyptic number.

90400978 is a deficient number, since it is larger than the sum of its proper divisors (45200492).

90400978 is a wasteful number, since it uses less digits than its factorization.

90400978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45200491.

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 90400978 is about 9507.9428900262. The cubic root of 90400978 is about 448.8050237850.

It can be divided in two parts, 90400 and 978, that added together give a triangular number (91378 = T₄₂₇).

The spelling of 90400978 in words is "ninety million, four hundred thousand, nine hundred seventy-eight".