21673685 has 16 divisors (see below), whose sum is σ = 28486080. Its totient is φ = 15699840.

The previous prime is 21673651. The next prime is 21673703. The reversal of 21673685 is 58637612.

It is a de Polignac number, because none of the positive numbers 2^k-21673685 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16586 + ... + 17844.

It is an arithmetic number, because the mean of its divisors is an integer number (1780380).

Almost surely, 2^21673685 is an apocalyptic number.

It is an amenable number.

21673685 is a deficient number, since it is larger than the sum of its proper divisors (6812395).

21673685 is a wasteful number, since it uses less digits than its factorization.

21673685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1588.

The product of its digits is 60480, while the sum is 38.

The square root of 21673685 is about 4655.5005101493. The cubic root of 21673685 is about 278.8116515889.

It can be divided in two parts, 2167368 and 5, that multiplied together give a triangular number (10836840 = T₄₆₅₅).

The spelling of 21673685 in words is "twenty-one million, six hundred seventy-three thousand, six hundred eighty-five".