21379131 has 6 divisors (see below), whose sum is σ = 30880980. Its totient is φ = 14252748.

The previous prime is 21379129. The next prime is 21379157. The reversal of 21379131 is 13197312.

It is not a de Polignac number, because 21379131 - 2¹ = 21379129 is a prime.

It is a super-2 number, since 2×21379131² = 914134484630322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21379095 and 21379104.

It is not an unprimeable number, because it can be changed into a prime (21379531) 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, 1187721 + ... + 1187738.

It is an arithmetic number, because the mean of its divisors is an integer number (5146830).

Almost surely, 2^21379131 is an apocalyptic number.

21379131 is a deficient number, since it is larger than the sum of its proper divisors (9501849).

21379131 is a wasteful number, since it uses less digits than its factorization.

21379131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2375465 (or 2375462 counting only the distinct ones).

The product of its digits is 1134, while the sum is 27.

The square root of 21379131 is about 4623.7572384372. The cubic root of 21379131 is about 277.5428324437.

The spelling of 21379131 in words is "twenty-one million, three hundred seventy-nine thousand, one hundred thirty-one".