21379797 has 12 divisors (see below), whose sum is σ = 30954924. Its totient is φ = 14219520.

The previous prime is 21379763. The next prime is 21379817. The reversal of 21379797 is 79797312.

It can be written as a sum of positive squares in 2 ways, for example, as 10150596 + 11229201 = 3186^2 + 3351^2 .

It is not a de Polignac number, because 21379797 - 2¹⁴ = 21363413 is a prime.

It is a super-2 number, since 2×21379797² = 914191439522418, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21379697) 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 11 ways as a sum of consecutive naturals, for example, 1573 + ... + 6725.

It is an arithmetic number, because the mean of its divisors is an integer number (2579577).

Almost surely, 2^21379797 is an apocalyptic number.

It is an amenable number.

21379797 is a deficient number, since it is larger than the sum of its proper divisors (9575127).

21379797 is a wasteful number, since it uses less digits than its factorization.

21379797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5620 (or 5617 counting only the distinct ones).

The product of its digits is 166698, while the sum is 45.

The square root of 21379797 is about 4623.8292572283. The cubic root of 21379797 is about 277.5457144069.

The spelling of 21379797 in words is "twenty-one million, three hundred seventy-nine thousand, seven hundred ninety-seven".