21387877 has 8 divisors (see below), whose sum is σ = 25286400. Its totient is φ = 17700144.

The previous prime is 21387851. The next prime is 21387893. The reversal of 21387877 is 77878312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21387877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387077) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52477 + ... + 52882.

It is an arithmetic number, because the mean of its divisors is an integer number (3160800).

Almost surely, 2^21387877 is an apocalyptic number.

It is an amenable number.

21387877 is a deficient number, since it is larger than the sum of its proper divisors (3898523).

21387877 is a wasteful number, since it uses less digits than its factorization.

21387877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105395.

The product of its digits is 131712, while the sum is 43.

The square root of 21387877 is about 4624.7029093770. The cubic root of 21387877 is about 277.5806739986.

The spelling of 21387877 in words is "twenty-one million, three hundred eighty-seven thousand, eight hundred seventy-seven".