21861370 has 16 divisors (see below), whose sum is σ = 39826080. Its totient is φ = 8638864.

The previous prime is 21861341. The next prime is 21861373. The reversal of 21861370 is 7316812.

It is not an unprimeable number, because it can be changed into a prime (21861373) 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, 12340 + ... + 13999.

It is an arithmetic number, because the mean of its divisors is an integer number (2489130).

Almost surely, 2^21861370 is an apocalyptic number.

21861370 is a deficient number, since it is larger than the sum of its proper divisors (17964710).

21861370 is a wasteful number, since it uses less digits than its factorization.

21861370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26429.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21861370 is about 4675.6143981299. The cubic root of 21861370 is about 279.6141368603.

The spelling of 21861370 in words is "twenty-one million, eight hundred sixty-one thousand, three hundred seventy".