21421377 has 12 divisors (see below), whose sum is σ = 32762340. Its totient is φ = 13440768.

The previous prime is 21421373. The next prime is 21421397. The reversal of 21421377 is 77312412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 14017536 + 7403841 = 3744^2 + 2721^2 .

It is not a de Polignac number, because 21421377 - 2² = 21421373 is a prime.

It is a super-2 number, since 2×21421377² = 917750785152258, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21421377.

It is not an unprimeable number, because it can be changed into a prime (21421373) 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, 69852 + ... + 70157.

It is an arithmetic number, because the mean of its divisors is an integer number (2730195).

Almost surely, 2^21421377 is an apocalyptic number.

It is an amenable number.

21421377 is a deficient number, since it is larger than the sum of its proper divisors (11340963).

21421377 is a wasteful number, since it uses less digits than its factorization.

21421377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140032 (or 140029 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21421377 is about 4628.3233465263. The cubic root of 21421377 is about 277.7255239962.

Adding to 21421377 its reverse (77312412), we get a palindrome (98733789).

The spelling of 21421377 in words is "twenty-one million, four hundred twenty-one thousand, three hundred seventy-seven".