87767921 has 4 divisors (see below), whose sum is σ = 89908644. Its totient is φ = 85627200.

The previous prime is 87767903. The next prime is 87767929. The reversal of 87767921 is 12976778.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12976778 = 2 ⋅6488389.

It can be written as a sum of positive squares in 2 ways, for example, as 37994896 + 49773025 = 6164^2 + 7055^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-87767921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87767929) 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, 1070300 + ... + 1070381.

It is an arithmetic number, because the mean of its divisors is an integer number (22477161).

Almost surely, 2^87767921 is an apocalyptic number.

It is an amenable number.

87767921 is a deficient number, since it is larger than the sum of its proper divisors (2140723).

87767921 is a wasteful number, since it uses less digits than its factorization.

87767921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2140722.

The product of its digits is 296352, while the sum is 47.

The square root of 87767921 is about 9368.4535009787. The cubic root of 87767921 is about 444.4046594225.

It can be divided in two parts, 87767 and 921, that added together give a palindrome (88688).

The spelling of 87767921 in words is "eighty-seven million, seven hundred sixty-seven thousand, nine hundred twenty-one".