21974393 has 12 divisors (see below), whose sum is σ = 26908560. Its totient is φ = 17843112.

The previous prime is 21974369. The next prime is 21974413. The reversal of 21974393 is 39347912.

It is not a de Polignac number, because 21974393 - 2¹² = 21970297 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21974993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10871 + ... + 12732.

It is an arithmetic number, because the mean of its divisors is an integer number (2242380).

Almost surely, 2^21974393 is an apocalyptic number.

It is an amenable number.

21974393 is a deficient number, since it is larger than the sum of its proper divisors (4934167).

21974393 is a wasteful number, since it uses less digits than its factorization.

21974393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23636 (or 23629 counting only the distinct ones).

The product of its digits is 40824, while the sum is 38.

The square root of 21974393 is about 4687.6852496728. The cubic root of 21974393 is about 280.0951759780.

It can be divided in two parts, 2197 and 4393, that multiplied together give a triangular number (9651421 = T₄₃₉₃).

The spelling of 21974393 in words is "twenty-one million, nine hundred seventy-four thousand, three hundred ninety-three".