21880621 has 4 divisors (see below), whose sum is σ = 25006432. Its totient is φ = 18754812.

The previous prime is 21880591. The next prime is 21880643. The reversal of 21880621 is 12608812.

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 not a de Polignac number, because 21880621 - 2⁵ = 21880589 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21880621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21880121) 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, 1562895 + ... + 1562908.

It is an arithmetic number, because the mean of its divisors is an integer number (6251608).

Almost surely, 2^21880621 is an apocalyptic number.

It is an amenable number.

21880621 is a deficient number, since it is larger than the sum of its proper divisors (3125811).

21880621 is an equidigital number, since it uses as much as digits as its factorization.

21880621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3125810.

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 21880621 is about 4677.6726050462. The cubic root of 21880621 is about 279.6961883280.

The spelling of 21880621 in words is "twenty-one million, eight hundred eighty thousand, six hundred twenty-one".