87990421 has 4 divisors (see below), whose sum is σ = 88378272. Its totient is φ = 87602572.

The previous prime is 87990401. The next prime is 87990443. The reversal of 87990421 is 12409978.

It is the 3830-th star number.

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.

It is a cyclic number.

It is not a de Polignac number, because 87990421 - 2⁵ = 87990389 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87990401) 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, 193585 + ... + 194038.

It is an arithmetic number, because the mean of its divisors is an integer number (22094568).

Almost surely, 2^87990421 is an apocalyptic number.

It is an amenable number.

87990421 is a deficient number, since it is larger than the sum of its proper divisors (387851).

87990421 is a wasteful number, since it uses less digits than its factorization.

87990421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 387850.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 87990421 is about 9380.3209433366. The cubic root of 87990421 is about 444.7798785091.

The spelling of 87990421 in words is "eighty-seven million, nine hundred ninety thousand, four hundred twenty-one".