21770621 has 4 divisors (see below), whose sum is σ = 21901152. Its totient is φ = 21640092.

The previous prime is 21770611. The next prime is 21770629. The reversal of 21770621 is 12607712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21770621 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 (21770629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65015 + ... + 65348.

It is an arithmetic number, because the mean of its divisors is an integer number (5475288).

Almost surely, 2^21770621 is an apocalyptic number.

It is an amenable number.

21770621 is a deficient number, since it is larger than the sum of its proper divisors (130531).

21770621 is a wasteful number, since it uses less digits than its factorization.

21770621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130530.

The product of its (nonzero) digits is 1176, while the sum is 26.

The square root of 21770621 is about 4665.8998060396. The cubic root of 21770621 is about 279.2266970432.

The spelling of 21770621 in words is "twenty-one million, seven hundred seventy thousand, six hundred twenty-one".