21431377 has 24 divisors (see below), whose sum is σ = 25482240. Its totient is φ = 17851680.

The previous prime is 21431359. The next prime is 21431383. The reversal of 21431377 is 77313412.

It is a de Polignac number, because none of the positive numbers 2^k-21431377 is a prime.

It is a super-2 number, since 2×21431377² = 918607840232258, which contains 22 as substring.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21431317) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 168688 + ... + 168814.

It is an arithmetic number, because the mean of its divisors is an integer number (1061760).

Almost surely, 2^21431377 is an apocalyptic number.

It is an amenable number.

21431377 is a deficient number, since it is larger than the sum of its proper divisors (4050863).

21431377 is a wasteful number, since it uses less digits than its factorization.

21431377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213 (or 190 counting only the distinct ones).

The product of its digits is 3528, while the sum is 28.

The square root of 21431377 is about 4629.4035252935. The cubic root of 21431377 is about 277.7687335307.

Adding to 21431377 its reverse (77313412), we get a palindrome (98744789).

The spelling of 21431377 in words is "twenty-one million, four hundred thirty-one thousand, three hundred seventy-seven".