21929401 has 16 divisors (see below), whose sum is σ = 25401600. Its totient is φ = 18759168.

The previous prime is 21929393. The next prime is 21929437. The reversal of 21929401 is 10492912.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21929401 - 2³ = 21929393 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21929401.

It is not an unprimeable number, because it can be changed into a prime (21929461) 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, 10665 + ... + 12553.

It is an arithmetic number, because the mean of its divisors is an integer number (1587600).

Almost surely, 2^21929401 is an apocalyptic number.

It is an amenable number.

21929401 is a deficient number, since it is larger than the sum of its proper divisors (3472199).

21929401 is a wasteful number, since it uses less digits than its factorization.

21929401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1968.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21929401 is about 4682.8838337076. The cubic root of 21929401 is about 279.9038828254.

The spelling of 21929401 in words is "twenty-one million, nine hundred twenty-nine thousand, four hundred one".