87978431 has 4 divisors (see below), whose sum is σ = 91012200. Its totient is φ = 84944664.

The previous prime is 87978419. The next prime is 87978461. The reversal of 87978431 is 13487978.

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 87978431 - 2⁶ = 87978367 is a prime.

It is a super-2 number, since 2×87978431² = 15480408642443522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87978461) 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, 1516841 + ... + 1516898.

It is an arithmetic number, because the mean of its divisors is an integer number (22753050).

Almost surely, 2^87978431 is an apocalyptic number.

87978431 is a deficient number, since it is larger than the sum of its proper divisors (3033769).

87978431 is a wasteful number, since it uses less digits than its factorization.

87978431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3033768.

The product of its digits is 338688, while the sum is 47.

The square root of 87978431 is about 9379.6818176311. The cubic root of 87978431 is about 444.7596749728.

The spelling of 87978431 in words is "eighty-seven million, nine hundred seventy-eight thousand, four hundred thirty-one".