21953139 has 8 divisors (see below), whose sum is σ = 31522512. Its totient is φ = 13509600.

The previous prime is 21953051. The next prime is 21953143. The reversal of 21953139 is 93135912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21953139 - 2⁷ = 21953011 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21953149) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 281412 + ... + 281489.

It is an arithmetic number, because the mean of its divisors is an integer number (3940314).

Almost surely, 2^21953139 is an apocalyptic number.

21953139 is a deficient number, since it is larger than the sum of its proper divisors (9569373).

21953139 is a wasteful number, since it uses less digits than its factorization.

21953139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562917.

The product of its digits is 7290, while the sum is 33.

The square root of 21953139 is about 4685.4176974951. The cubic root of 21953139 is about 280.0048426033.

The spelling of 21953139 in words is "twenty-one million, nine hundred fifty-three thousand, one hundred thirty-nine".