21219669 has 6 divisors (see below), whose sum is σ = 30650646. Its totient is φ = 14146440.

The previous prime is 21219641. The next prime is 21219703. The reversal of 21219669 is 96691212.

It can be written as a sum of positive squares in only one way, i.e., 19980900 + 1238769 = 4470^2 + 1113^2 .

It is not a de Polignac number, because 21219669 - 2¹¹ = 21217621 is a prime.

It is a super-2 number, since 2×21219669² = 900548704939122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21219169) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1178862 + ... + 1178879.

It is an arithmetic number, because the mean of its divisors is an integer number (5108441).

Almost surely, 2^21219669 is an apocalyptic number.

It is an amenable number.

21219669 is a deficient number, since it is larger than the sum of its proper divisors (9430977).

21219669 is a wasteful number, since it uses less digits than its factorization.

21219669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2357747 (or 2357744 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 21219669 is about 4606.4811950121. The cubic root of 21219669 is about 276.8510670493.

It can be divided in two parts, 212 and 19669, that added together give a square (19881 = 141²).

The spelling of 21219669 in words is "twenty-one million, two hundred nineteen thousand, six hundred sixty-nine".