21431445 has 32 divisors (see below), whose sum is σ = 39363840. Its totient is φ = 9753600.

The previous prime is 21431401. The next prime is 21431489. The reversal of 21431445 is 54413412.

It is an interprime number because it is at equal distance from previous prime (21431401) and next prime (21431489).

It is not a de Polignac number, because 21431445 - 2⁷ = 21431317 is a prime.

It is a super-3 number, since 3×21431445³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41851 + ... + 42359.

It is an arithmetic number, because the mean of its divisors is an integer number (1230120).

Almost surely, 2^21431445 is an apocalyptic number.

It is an amenable number.

21431445 is a deficient number, since it is larger than the sum of its proper divisors (17932395).

21431445 is a wasteful number, since it uses less digits than its factorization.

21431445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 925.

The product of its digits is 1920, while the sum is 24.

The square root of 21431445 is about 4629.4108696464. The cubic root of 21431445 is about 277.7690273095.

Adding to 21431445 its reverse (54413412), we get a palindrome (75844857).

The spelling of 21431445 in words is "twenty-one million, four hundred thirty-one thousand, four hundred forty-five".