21260691 has 8 divisors (see below), whose sum is σ = 31497360. Its totient is φ = 14173776.

The previous prime is 21260669. The next prime is 21260711. The reversal of 21260691 is 19606212.

It is a de Polignac number, because none of the positive numbers 2^k-21260691 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 787433 = 21260691 / (2 + 1 + 2 + 6 + 0 + 6 + 9 + 1).

It is not an unprimeable number, because it can be changed into a prime (21260621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 393690 + ... + 393743.

It is an arithmetic number, because the mean of its divisors is an integer number (3937170).

Almost surely, 2^21260691 is an apocalyptic number.

21260691 is a deficient number, since it is larger than the sum of its proper divisors (10236669).

21260691 is an equidigital number, since it uses as much as digits as its factorization.

21260691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 787442 (or 787436 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21260691 is about 4610.9316845948. The cubic root of 21260691 is about 277.0293556276.

The spelling of 21260691 in words is "twenty-one million, two hundred sixty thousand, six hundred ninety-one".