21370687 has 16 divisors (see below), whose sum is σ = 25016320. Its totient is φ = 18079200.

The previous prime is 21370681. The next prime is 21370693. The reversal of 21370687 is 78607312.

It is an interprime number because it is at equal distance from previous prime (21370681) and next prime (21370693).

It is a de Polignac number, because none of the positive numbers 2^k-21370687 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 (21370681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6262 + ... + 9052.

It is an arithmetic number, because the mean of its divisors is an integer number (1563520).

Almost surely, 2^21370687 is an apocalyptic number.

21370687 is a deficient number, since it is larger than the sum of its proper divisors (3645633).

21370687 is a wasteful number, since it uses less digits than its factorization.

21370687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2854.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 21370687 is about 4622.8440380355. The cubic root of 21370687 is about 277.5062877671.

Adding to 21370687 its reverse (78607312), we get a palindrome (99977999).

The spelling of 21370687 in words is "twenty-one million, three hundred seventy thousand, six hundred eighty-seven".