21862649 has 4 divisors (see below), whose sum is σ = 21921636. Its totient is φ = 21803664.

The previous prime is 21862637. The next prime is 21862651. The reversal of 21862649 is 94626812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18550249 + 3312400 = 4307^2 + 1820^2 .

It is a cyclic number.

It is not a de Polignac number, because 21862649 - 2¹² = 21858553 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21862609) 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, 28934 + ... + 29679.

It is an arithmetic number, because the mean of its divisors is an integer number (5480409).

Almost surely, 2^21862649 is an apocalyptic number.

It is an amenable number.

21862649 is a deficient number, since it is larger than the sum of its proper divisors (58987).

21862649 is an equidigital number, since it uses as much as digits as its factorization.

21862649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58986.

The product of its digits is 41472, while the sum is 38.

The square root of 21862649 is about 4675.7511695983. The cubic root of 21862649 is about 279.6195896980.

The spelling of 21862649 in words is "twenty-one million, eight hundred sixty-two thousand, six hundred forty-nine".