21870623 has 4 divisors (see below), whose sum is σ = 21882840. Its totient is φ = 21858408.

The previous prime is 21870599. The next prime is 21870643. The reversal of 21870623 is 32607812.

It is a happy number.

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 21870623 - 2⁶ = 21870559 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 (21870643) 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, 2840 + ... + 7197.

It is an arithmetic number, because the mean of its divisors is an integer number (5470710).

Almost surely, 2^21870623 is an apocalyptic number.

21870623 is a deficient number, since it is larger than the sum of its proper divisors (12217).

21870623 is a wasteful number, since it uses less digits than its factorization.

21870623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12216.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21870623 is about 4676.6037890760. The cubic root of 21870623 is about 279.6535809370.

The spelling of 21870623 in words is "twenty-one million, eight hundred seventy thousand, six hundred twenty-three".