28171421 has 2 divisors, whose sum is σ = 28171422. Its totient is φ = 28171420.

The previous prime is 28171411. The next prime is 28171463. The reversal of 28171421 is 12417182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15132100 + 13039321 = 3890^2 + 3611^2 .

It is a cyclic number.

It is not a de Polignac number, because 28171421 - 2²² = 23977117 is a prime.

It is a super-2 number, since 2×28171421² = 1587257922318482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28171411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14085710 + 14085711.

It is an arithmetic number, because the mean of its divisors is an integer number (14085711).

Almost surely, 2^28171421 is an apocalyptic number.

It is an amenable number.

28171421 is a deficient number, since it is larger than the sum of its proper divisors (1).

28171421 is an equidigital number, since it uses as much as digits as its factorization.

28171421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 896, while the sum is 26.

The square root of 28171421 is about 5307.6756683128. The cubic root of 28171421 is about 304.2773215290.

The spelling of 28171421 in words is "twenty-eight million, one hundred seventy-one thousand, four hundred twenty-one".