21969129 has 16 divisors (see below), whose sum is σ = 36052352. Its totient is φ = 11587968.

The previous prime is 21969127. The next prime is 21969169. The reversal of 21969129 is 92196912.

It is not a de Polignac number, because 21969129 - 2¹ = 21969127 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21969127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39964 + ... + 40509.

It is an arithmetic number, because the mean of its divisors is an integer number (2253272).

Almost surely, 2^21969129 is an apocalyptic number.

It is an amenable number.

21969129 is a deficient number, since it is larger than the sum of its proper divisors (14083223).

21969129 is a wasteful number, since it uses less digits than its factorization.

21969129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80496.

The product of its digits is 17496, while the sum is 39.

The square root of 21969129 is about 4687.1237448994. The cubic root of 21969129 is about 280.0728084469.

It can be divided in two parts, 2196 and 9129, that added together give a triangular number (11325 = T₁₅₀).

The spelling of 21969129 in words is "twenty-one million, nine hundred sixty-nine thousand, one hundred twenty-nine".