21620377 has 4 divisors (see below), whose sum is σ = 21638416. Its totient is φ = 21602340.

The previous prime is 21620369. The next prime is 21620383. The reversal of 21620377 is 77302612.

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 21620377 - 2³ = 21620369 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21620317) 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, 7083 + ... + 9664.

It is an arithmetic number, because the mean of its divisors is an integer number (5409604).

Almost surely, 2^21620377 is an apocalyptic number.

It is an amenable number.

21620377 is a deficient number, since it is larger than the sum of its proper divisors (18039).

21620377 is a wasteful number, since it uses less digits than its factorization.

21620377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18038.

The product of its (nonzero) digits is 3528, while the sum is 28.

The square root of 21620377 is about 4649.7717148264. The cubic root of 21620377 is about 278.5828780993.

Adding to 21620377 its reverse (77302612), we get a palindrome (98922989).

The spelling of 21620377 in words is "twenty-one million, six hundred twenty thousand, three hundred seventy-seven".