21261699 has 6 divisors (see below), whose sum is σ = 30711356. Its totient is φ = 14174460.

The previous prime is 21261697. The next prime is 21261701. The reversal of 21261699 is 99616212.

It is an interprime number because it is at equal distance from previous prime (21261697) and next prime (21261701).

It is not a de Polignac number, because 21261699 - 2¹ = 21261697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21261697) 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 5 ways as a sum of consecutive naturals, for example, 1181197 + ... + 1181214.

Almost surely, 2^21261699 is an apocalyptic number.

21261699 is a deficient number, since it is larger than the sum of its proper divisors (9449657).

21261699 is a wasteful number, since it uses less digits than its factorization.

21261699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2362417 (or 2362414 counting only the distinct ones).

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

The square root of 21261699 is about 4611.0409887573. The cubic root of 21261699 is about 277.0337336788.

The spelling of 21261699 in words is "twenty-one million, two hundred sixty-one thousand, six hundred ninety-nine".